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/channels/slack/adapter.ts

@@ -287,6 +287,8 @@ export class SlackAdapter implements ChannelAdapter {
       }
     }
 
+    // Note: Slack doesn't expose a typing indicator API for bots
+
     // Build peer ID: channelId:threadTs (thread-aware)
     const threadTs = message.thread_ts ?? message.ts ?? '';
     const peerId = `${channelId}:${threadTs}`;