fix: resolve medium/low audit findings across backend and frontend

- ctx CLI: validate int() limit arg, wrap FTS5 MATCH in try/except
- ctx.rs: FTS5 error message clarity, Mutex::lock() returns Err not panic
- sdk-messages.ts: runtime type guards (str/num) replace bare `as` casts
- agent-runner.ts: strip ANTHROPIC_* env vars alongside CLAUDE*
- agent-dispatcher.ts: timestamps use seconds (match session.rs convention)
- remote.rs: disconnect handler uses lock().await not try_lock()
- session.rs: propagate pane_ids serialization error
- watcher.rs: reject root-level paths instead of silent no-op
- lib.rs: log warnings on profile.toml read failure and resource_dir error
- agent-bridge.ts: validate event payload is object before cast

v2/sidecar/agent-runner.ts

@@ -86,7 +86,7 @@ async function handleQuery(msg: QueryMessage) {
   // Strip CLAUDE* env vars to prevent nesting detection by the spawned CLI
   const cleanEnv: Record<string, string | undefined> = {};
   for (const [key, value] of Object.entries(process.env)) {
-    if (!key.startsWith('CLAUDE')) {
+    if (!key.startsWith('CLAUDE') && !key.startsWith('ANTHROPIC_')) {
       cleanEnv[key] = value;
     }
   }