feat: WarzonePhone lossy VoIP protocol — Phase 1 complete

Rust workspace with 7 crates implementing a custom VoIP protocol
designed for extremely lossy connections (5-70% loss, 100-500kbps,
300-800ms RTT). 89 tests passing across all crates.

Crates:
- wzp-proto: Wire format, traits, adaptive quality controller, jitter buffer, session FSM
- wzp-codec: Opus encoder/decoder (audiopus), Codec2 stubs, adaptive switching, resampling
- wzp-fec: RaptorQ fountain codes, interleaving, block management (proven 30-70% loss recovery)
- wzp-crypto: X25519+ChaCha20-Poly1305, Warzone identity compatible, anti-replay, rekeying
- wzp-transport: QUIC via quinn with DATAGRAM frames, path monitoring, signaling streams
- wzp-relay: Integration stub (Phase 2)
- wzp-client: Integration stub (Phase 2)

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

crates/wzp-proto/src/error.rs

@@ -0,0 +1,67 @@
+use thiserror::Error;
+
+/// Errors from audio codec operations.
+#[derive(Debug, Error)]
+pub enum CodecError {
+    #[error("encode failed: {0}")]
+    EncodeFailed(String),
+    #[error("decode failed: {0}")]
+    DecodeFailed(String),
+    #[error("unsupported profile transition from {from:?} to {to:?}")]
+    UnsupportedTransition {
+        from: crate::CodecId,
+        to: crate::CodecId,
+    },
+}
+
+/// Errors from FEC operations.
+#[derive(Debug, Error)]
+pub enum FecError {
+    #[error("source block is full (max {max} symbols)")]
+    BlockFull { max: usize },
+    #[error("decode impossible: need {needed} symbols, have {have}")]
+    InsufficientSymbols { needed: usize, have: usize },
+    #[error("invalid block id {0}")]
+    InvalidBlock(u8),
+    #[error("internal FEC error: {0}")]
+    Internal(String),
+}
+
+/// Errors from cryptographic operations.
+#[derive(Debug, Error)]
+pub enum CryptoError {
+    #[error("decryption failed (bad key or tampered data)")]
+    DecryptionFailed,
+    #[error("invalid public key")]
+    InvalidPublicKey,
+    #[error("rekey failed: {0}")]
+    RekeyFailed(String),
+    #[error("anti-replay: duplicate or old packet (seq={seq})")]
+    ReplayDetected { seq: u16 },
+    #[error("internal crypto error: {0}")]
+    Internal(String),
+}
+
+/// Errors from transport operations.
+#[derive(Debug, Error)]
+pub enum TransportError {
+    #[error("connection lost")]
+    ConnectionLost,
+    #[error("datagram too large: {size} bytes (max {max})")]
+    DatagramTooLarge { size: usize, max: usize },
+    #[error("connection timeout after {ms}ms")]
+    Timeout { ms: u64 },
+    #[error("io error: {0}")]
+    Io(#[from] std::io::Error),
+    #[error("internal transport error: {0}")]
+    Internal(String),
+}
+
+/// Errors from obfuscation layer.
+#[derive(Debug, Error)]
+pub enum ObfuscationError {
+    #[error("obfuscation failed: {0}")]
+    Failed(String),
+    #[error("deobfuscation failed: invalid framing")]
+    InvalidFraming,
+}