v0.0.22: version bump, ETH identity in web client, version bump rule

Version:
- Workspace + protocol: 0.0.21 → 0.0.22
- Web client VERSION: 0.0.17 → 0.0.22
- Service worker cache: wz-v2 → wz-v3

ETH identity:
- Added WasmIdentity::eth_address() export (derives from seed via secp256k1)
- Web client sends eth_address during key registration
- Identity display shows ETH address first, then fingerprint
- No more server-side resolve needed — computed client-side

CLAUDE.md:
- Added MANDATORY version bump rule (4 places to update)
- Must bump on every functional change, never skip SW cache

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

warzone/CLAUDE.md

@@ -1,5 +1,15 @@
 # featherChat — Design Principles & Conventions
 
+## MANDATORY: Version Bumping
+
+**After every set of changes that modifies functionality, bump the version:**
+1. `Cargo.toml` workspace version (e.g. `0.0.22` → `0.0.23`)
+2. `crates/warzone-protocol/Cargo.toml` standalone version (same)
+3. `crates/warzone-server/src/routes/web.rs` JS `VERSION` constant
+4. `crates/warzone-server/src/routes/web.rs` service worker `CACHE` version (`wz-vN` → `wz-v(N+1)`)
+
+Never commit functional changes without bumping all four. The service worker cache MUST be bumped or browsers will serve stale WASM.
+
 ## Architecture Principles
 
 1. **Single seed, multiple identities** — Ed25519 (messaging), X25519 (encryption), secp256k1 (ETH address) all derived from one BIP39 seed via HKDF with domain-separated info strings.