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/models/github.ts

@@ -137,6 +137,11 @@ export class GitHubModelsClient implements ModelClient {
       }));
     }
 
+    // Extended thinking/reasoning mode
+    if (request.thinking) {
+      (params as any).reasoning_effort = 'medium';
+    }
+
     const response = await this.client.chat.completions.create(params);
 
     const choice = response.choices[0];