v0.0.21: TUI overhaul, WZP call infrastructure, security hardening, federation

TUI:
- Split 1,756-line app.rs monolith into 7 modules (types, draw, commands, input, file_transfer, network, mod)
- Message timestamps [HH:MM], scrolling (PageUp/Down/arrows), connection status dot, unread badge
- /help command, terminal bell on incoming DM, /devices + /kick commands
- 44 unit tests (types, input, draw with TestBackend)

Server — WZP Call Infrastructure (FC-2/3/5/6/7/10):
- Call state management (CallState, CallStatus, active_calls, calls + missed_calls sled trees)
- WS call signal awareness (Offer/Answer/Hangup update state, missed call on offline)
- Group call endpoint (POST /groups/:name/call with SHA-256 room ID, fan-out)
- Presence API (GET /presence/:fp, POST /presence/batch)
- Missed call flush on WS reconnect
- WZP relay config + CORS

Server — Security (FC-P1):
- Auth enforcement middleware (AuthFingerprint extractor on 13 write handlers)
- Session auto-recovery (delete corrupted ratchet, show [session reset])
- WS connection cap (5/fingerprint) + global concurrency limit (200)
- Device management (GET /devices, POST /devices/:id/kick, POST /devices/revoke-all)

Server — Federation:
- Two-server federation via JSON config (--federation flag)
- Periodic presence sync (every 5s, full-state, self-healing)
- Message forwarding via HTTP POST with SHA-256(secret||body) auth
- Graceful degradation (peer down = queue locally)
- deliver_or_queue() replaces push-or-queue in ws.rs + messages.rs

Client — Group Messaging:
- SenderKeyDistribution storage + GroupSenderKey decryption in TUI
- sender_keys sled tree in LocalDb

WASM:
- All 8 WireMessage variants handled (no more "unsupported")
- decrypt_group_message() + create_sender_key_from_distribution() exports
- CallSignal parsing with signal_type mapping

Docs:
- ARCHITECTURE.md rewritten with Mermaid diagrams
- README.md created
- TASK_PLAN.md with FC-P{phase}-T{task} naming
- PROGRESS.md updated to v0.0.21

WZP submodule updated to 6f4e8eb (IAX2 trunking, adaptive quality, metrics, all S-tasks done)

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

warzone/crates/warzone-client/src/storage.rs

@@ -10,6 +10,7 @@ pub struct LocalDb {
     pre_keys: sled::Tree,
     contacts: sled::Tree,
     history: sled::Tree,
+    sender_keys: sled::Tree,
     _db: sled::Db,
 }
 
@@ -39,11 +40,13 @@ impl LocalDb {
         let pre_keys = db.open_tree("pre_keys")?;
         let contacts = db.open_tree("contacts")?;
         let history = db.open_tree("history")?;
+        let sender_keys = db.open_tree("sender_keys")?;
         Ok(LocalDb {
             sessions,
             pre_keys,
             contacts,
             history,
+            sender_keys,
             _db: db,
         })
     }
@@ -57,6 +60,14 @@ impl LocalDb {
         Ok(())
     }
 
+    /// Delete a ratchet session for a peer (used for session recovery).
+    pub fn delete_session(&self, peer: &Fingerprint) -> Result<()> {
+        let key = peer.to_hex();
+        self.sessions.remove(key.as_bytes())?;
+        self.sessions.flush()?;
+        Ok(())
+    }
+
     /// Load a ratchet session for a peer.
     pub fn load_session(&self, peer: &Fingerprint) -> Result<Option<RatchetState>> {
         let key = peer.to_hex();
@@ -115,6 +126,39 @@ impl LocalDb {
         }
     }
 
+    // ── Sender Keys ──
+
+    /// Save a sender key for a (sender, group) pair.
+    pub fn save_sender_key(
+        &self,
+        sender_fp: &str,
+        group_name: &str,
+        key: &warzone_protocol::sender_keys::SenderKey,
+    ) -> Result<()> {
+        let db_key = format!("sk:{}:{}", sender_fp, group_name);
+        let data = bincode::serialize(key).context("failed to serialize sender key")?;
+        self.sender_keys.insert(db_key.as_bytes(), data)?;
+        self.sender_keys.flush()?;
+        Ok(())
+    }
+
+    /// Load a sender key for a (sender, group) pair.
+    pub fn load_sender_key(
+        &self,
+        sender_fp: &str,
+        group_name: &str,
+    ) -> Result<Option<warzone_protocol::sender_keys::SenderKey>> {
+        let db_key = format!("sk:{}:{}", sender_fp, group_name);
+        match self.sender_keys.get(db_key.as_bytes())? {
+            Some(data) => {
+                let key = bincode::deserialize(&data)
+                    .context("failed to deserialize sender key")?;
+                Ok(Some(key))
+            }
+            None => Ok(None),
+        }
+    }
+
     // ── Contacts ──
 
     /// Add or update a contact. Called on send/receive.