v0.0.28: BotFather-only registration, per-instance bot toggle, docs update

Security:
- Bot registration restricted to BotFather (requires botfather_token)
- Direct POST /v1/bot/register without BotFather auth → rejected

Deploy:
- systemd service reads /home/warzone/server.env for EXTRA_ARGS
- deploy/warzone-server.env.mequ: no bots (default)
- deploy/warzone-server.env.kh3rad3ree: --enable-bots
- setup.sh copies per-hostname env file

Docs updated:
- LLM_HELP.md: BotFather flow, plaintext bot messaging, E2E option, bridge
- LLM_BOT_DEV.md: botfather_token requirement, E2E mode, bridge section
- BOT_API.md: full BotFather flow, ownership, numeric IDs, webhook delivery
- SERVER.md: --enable-bots flag, per-instance config, bot system section
- USAGE.md: bot messaging, BotFather, bridge tool

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

warzone/crates/warzone-server/src/routes/web.rs

@@ -50,7 +50,7 @@ async fn pwa_manifest() -> impl IntoResponse {
 
 async fn service_worker() -> impl IntoResponse {
     ([(header::CONTENT_TYPE, "application/javascript")], r##"
-const CACHE = 'wz-v9';
+const CACHE = 'wz-v10';
 const SHELL = ['/', '/wasm/warzone_wasm.js', '/wasm/warzone_wasm_bg.wasm', '/icon.svg', '/manifest.json'];
 
 self.addEventListener('install', e => {
@@ -241,7 +241,7 @@ let pollTimer = null;
 let ws = null;  // WebSocket connection
 let wasmReady = false;
 
-const VERSION = '0.0.27';
+const VERSION = '0.0.28';
 let DEBUG = true;  // toggle with /debug command
 
 // ── Receipt tracking ──