Add client syslog events, fix client UDP TX error threshold

- Client mode now emits TEST_START and TEST_END syslog events
- Client UDP TX threshold raised from 1000 to 50000 with adaptive backoff
  (matching server behavior) — prevents premature TX death on macOS
- Updated all docs (README, user-guide, architecture, protocol, docker)
- Added results.csv to gitignore

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/architecture.md

@@ -13,22 +13,31 @@ graph TB
     client["client.rs<br/>Client mode"]
     protocol["protocol.rs<br/>Wire protocol types"]
     auth["auth.rs<br/>MD5 authentication"]
+    ecsrp5["ecsrp5.rs<br/>EC-SRP5 authentication<br/>(Curve25519 Weierstrass)"]
     bandwidth["bandwidth.rs<br/>Rate control & reporting"]
+    csv_output["csv_output.rs<br/>CSV result logging"]
+    syslog["syslog_logger.rs<br/>Remote syslog (RFC 3164)"]
     lib["lib.rs<br/>Public API for tests"]
 
     main --> server
     main --> client
     main --> bandwidth
+    main --> csv_output
+    main --> syslog
     server --> protocol
     server --> auth
+    server --> ecsrp5
     server --> bandwidth
+    server --> syslog
     client --> protocol
     client --> auth
+    client --> ecsrp5
     client --> bandwidth
     lib --> server
     lib --> client
     lib --> protocol
     lib --> auth
+    lib --> ecsrp5
     lib --> bandwidth
 ```
 
@@ -60,8 +69,8 @@ sequenceDiagram
         SRV->>TCP: EC-SRP5 [03 00 00 00]
         MK->>TCP: [len][username\0][client_pubkey:32][parity:1]
         SRV->>TCP: [len][server_pubkey:32][parity:1][salt:16]
-        MK->>TCP: [len][client_proof:32]
-        SRV->>TCP: [len][server_proof:32]
+        MK->>TCP: [len][client_confirmation:32]
+        SRV->>TCP: [len][server_confirmation:32]
         Note over SRV: Curve25519 Weierstrass EC-SRP5<br/>See docs/ecsrp5-research.md
         SRV->>TCP: AUTH_OK [01 00 00 00]
     end
@@ -105,14 +114,18 @@ sequenceDiagram
     CLI->>TCP: Command [16 bytes]
     Note over CLI: direction bits tell server<br/>what to do (TX/RX/BOTH)
 
-    alt Auth response 01
+    alt Auth response 01 (no auth)
         Note over CLI: No auth, proceed
     else Auth response 02 (MD5)
-        MK->>TCP: Challenge
-        CLI->>TCP: MD5 response
+        MK->>TCP: Challenge [16 random bytes]
+        CLI->>TCP: MD5 response [48 bytes]
         MK->>TCP: AUTH_OK
     else Auth response 03 (EC-SRP5)
-        Note over CLI: Not supported yet
+        CLI->>TCP: [len][username\0][client_pubkey:32][parity:1]
+        MK->>TCP: [len][server_pubkey:32][parity:1][salt:16]
+        CLI->>TCP: [len][client_confirmation:32]
+        MK->>TCP: [len][server_confirmation:32]
+        MK->>TCP: AUTH_OK
     end
 
     Note over CLI,MK: Data transfer begins<br/>(TCP or UDP, same as server)
@@ -156,57 +169,81 @@ graph TB
 ## Key Design Decisions
 
 ### 1. Tokio async runtime
+
 All I/O is async via tokio. Each client connection spawns independent tasks for TX, RX, and status exchange. This allows handling hundreds of concurrent connections on a single thread pool.
 
 ### 2. Lock-free shared state
-TX/RX threads and the status loop share bandwidth counters via `AtomicU64`. No mutexes needed — `swap(0)` atomically reads and resets counters each interval.
+
+TX/RX threads and the status loop share bandwidth counters via `AtomicU64`. No mutexes needed -- `swap(0)` atomically reads and resets counters each interval.
 
 ### 3. Sequential status loop (matching C pselect)
+
 The UDP status exchange uses a sequential timeout-read-then-send pattern rather than `tokio::select!`. This ensures our status messages are sent exactly every 1 second, preventing MikroTik's speed adaptation from seeing irregular feedback.
 
 ### 4. Direction bits from server perspective
+
 The direction byte in the protocol means what the **server** should do:
 - `0x01` (CMD_DIR_RX) = server receives
 - `0x02` (CMD_DIR_TX) = server transmits
 - `0x03` (CMD_DIR_BOTH) = bidirectional
 
-The client inverts before sending: client "transmit" → `CMD_DIR_RX` (telling server to receive).
+The client inverts before sending: client "transmit" sends `CMD_DIR_RX` (telling server to receive).
 
 ### 5. TCP socket half keepalive
+
 When only one direction is active (e.g., TX only), the unused socket half is kept alive. Dropping `OwnedWriteHalf` sends a TCP FIN, which MikroTik interprets as disconnection.
 
 ### 6. Static musl binary
-Release builds use musl for a fully static binary with zero runtime dependencies. The binary is 2 MB and runs on any Linux.
+
+Release builds use musl for a fully static binary with zero runtime dependencies. The binary is approximately 2 MB and runs on any Linux distribution.
+
+### 7. EC-SRP5 with big integer arithmetic
+
+The EC-SRP5 implementation uses `num-bigint` for Curve25519 Weierstrass-form elliptic curve arithmetic. MikroTik's authentication uses the Weierstrass form (not the more common Montgomery or Edwards forms), requiring direct field arithmetic over the prime `2^255 - 19`. The implementation includes point multiplication, `lift_x`, `redp1` (hash-to-curve), and Montgomery coordinate conversion.
+
+### 8. Global singletons for syslog and CSV
+
+The syslog and CSV modules use `Mutex<Option<...>>` global statics. This avoids threading state through every function call while remaining safe. Both modules are initialized once at startup and used from any async task via their public API functions.
 
 ## File Layout
 
 ```
 btest-rs/
 ├── src/
-│   ├── main.rs          # CLI entry point, argument parsing
-│   ├── lib.rs           # Public API (used by integration tests)
-│   ├── protocol.rs      # Wire format: Command, StatusMessage, constants
-│   ├── auth.rs          # MD5 challenge-response authentication
-│   ├── ecsrp5.rs        # EC-SRP5 authentication (Curve25519 Weierstrass)
-│   ├── server.rs        # Server mode: listener, TCP/UDP handlers
-│   ├── client.rs        # Client mode: connector, TCP/UDP handlers
-│   └── bandwidth.rs     # Rate limiting, formatting, shared state
+│   ├── main.rs              # CLI entry point, argument parsing (clap)
+│   ├── lib.rs               # Public API (used by integration tests)
+│   ├── protocol.rs          # Wire format: Command, StatusMessage, constants
+│   ├── auth.rs              # MD5 challenge-response authentication
+│   ├── ecsrp5.rs            # EC-SRP5 authentication (Curve25519 Weierstrass)
+│   ├── server.rs            # Server mode: listener, TCP/UDP handlers
+│   ├── client.rs            # Client mode: connector, TCP/UDP handlers
+│   ├── bandwidth.rs         # Rate limiting, formatting, shared state
+│   ├── csv_output.rs        # CSV result logging (append-mode, auto-header)
+│   └── syslog_logger.rs     # Remote syslog sender (RFC 3164 / BSD format)
 ├── tests/
 │   └── integration_test.rs  # End-to-end server/client tests
 ├── scripts/
-│   ├── build-linux.sh       # Cross-compile for x86_64 Linux
-│   ├── install-service.sh   # systemd service installer
-│   ├── test-local.sh        # Loopback self-test
-│   ├── test-mikrotik.sh     # Test against MikroTik device
-│   └── test-docker.sh       # Docker container test
+│   ├── build-linux.sh           # Cross-compile for x86_64 Linux (musl)
+│   ├── build-macos-release.sh   # macOS release build
+│   ├── install-service.sh       # systemd service installer
+│   ├── push-docker.sh           # Push Docker image to registry
+│   ├── test-local.sh            # Loopback self-test
+│   ├── test-mikrotik.sh         # Test against MikroTik device
+│   ├── test-docker.sh           # Docker container test
+│   └── debug-capture.sh         # Packet capture for debugging
 ├── docs/
-│   ├── architecture.md      # This file
-│   ├── protocol.md          # Protocol specification
-│   ├── user-guide.md        # Usage documentation
-│   └── docker.md            # Docker & deployment guide
-├── Dockerfile               # Production Docker image
-├── Dockerfile.cross         # Cross-compilation for Linux x86_64
-├── docker-compose.yml       # Docker Compose configuration
-├── Cargo.toml
-└── btest-opensource/        # Original C implementation (git submodule)
+│   ├── architecture.md          # This file
+│   ├── protocol.md              # Protocol specification
+│   ├── user-guide.md            # Usage documentation
+│   ├── docker.md                # Docker & deployment guide
+│   ├── ecsrp5-research.md       # EC-SRP5 reverse-engineering notes
+│   └── man/
+│       └── btest.1              # Unix manual page (troff format)
+├── Dockerfile                   # Production Docker image (multi-stage)
+├── Dockerfile.cross             # Cross-compilation for Linux x86_64
+├── docker-compose.yml           # Docker Compose configuration
+├── Cargo.toml                   # Rust package manifest
+├── Cargo.lock                   # Dependency lock file
+├── LICENSE                      # MIT License
+└── btest-opensource/            # Original C implementation (git submodule)
 ```