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/store.ts

@@ -1,6 +1,15 @@
 import Database from 'better-sqlite3';
 import type { Message } from '../models/types.js';
 
+/** Parse a duration string like '30d', '7d', '12h' to milliseconds. Returns null if invalid or '0'. */
+export function parseDuration(s: string): number | null {
+  if (s === '0' || s === 'false') return null;
+  const match = s.match(/^(\d+)(h|d)$/);
+  if (!match) return null;
+  const [, n, unit] = match;
+  return unit === 'h' ? Number(n) * 3600_000 : Number(n) * 86_400_000;
+}
+
 export class SessionStore {
   private db: Database.Database;
 
@@ -71,6 +80,27 @@ export class SessionStore {
     return rows.map(row => row.session_id);
   }
 
+  /** Delete all messages for sessions with no activity since the given timestamp. Returns pruned session IDs. */
+  pruneStale(beforeTimestamp: number): string[] {
+    const stale = this.db.prepare(`
+      SELECT session_id FROM messages
+      GROUP BY session_id
+      HAVING MAX(created_at) < ?
+    `).all(beforeTimestamp) as Array<{ session_id: string }>;
+
+    if (stale.length === 0) return [];
+
+    const deleteStmt = this.db.prepare('DELETE FROM messages WHERE session_id = ?');
+    const transaction = this.db.transaction(() => {
+      for (const { session_id } of stale) {
+        deleteStmt.run(session_id);
+      }
+    });
+    transaction();
+
+    return stale.map(r => r.session_id);
+  }
+
   close(): void {
     this.db.close();
   }