feat: implement tier 1 quick wins (tool groups, typing, pruning, verbose, think)

Five additive features with no breaking changes:

- Tool groups: group:fs, group:runtime, group:web, group:memory syntactic
  sugar for allow/deny lists in tool policy config
- Typing indicators: Discord sendTyping() and WhatsApp sendStateTyping()
  on message receipt for better UX feedback
- Session pruning: TTL-based auto-cleanup via sessions.ttl config with
  hourly daemon timer and SQLite GROUP BY pruning
- /verbose command: TUI command parser toggle for raw streaming display
- !!think prefix: per-message extended thinking mode wired through
  Anthropic (budget_tokens), OpenAI/GitHub (reasoning_effort), and
  Gemini (thinkingConfig) providers

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/session/manager.ts

@@ -98,4 +98,11 @@ export class SessionManager {
     const id = this.makeSessionId(frontend, userId);
     this.sessions.delete(id);
   }
+
+  /** Remove sessions from the in-memory cache by their IDs. */
+  evictSessions(sessionIds: string[]): void {
+    for (const id of sessionIds) {
+      this.sessions.delete(id);
+    }
+  }
 }