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/backends/native/agent.ts

@@ -51,6 +51,7 @@ export class NativeAgent {
   private _callCount: number = 0;
   private _toolPolicyContext?: ToolPolicyContext;
   private _attachmentCollector?: OutboundAttachmentCollector;
+  private _thinking: boolean = false;
 
   constructor(config: NativeAgentConfig) {
     this.modelClient = config.modelClient;
@@ -69,6 +70,14 @@ export class NativeAgent {
   }
 
   async process(userMessage: string, attachments?: Attachment[]): Promise<string> {
+    // Detect and strip !!think prefix for per-message thinking mode
+    if (userMessage.startsWith('!!think ') || userMessage === '!!think') {
+      this._thinking = true;
+      userMessage = userMessage.replace(/^!!think\s*/, '').trim() || 'Think about this.';
+    } else {
+      this._thinking = false;
+    }
+
     const userMsg = buildUserMessage(userMessage, attachments);
 
     if (this.session) {
@@ -89,6 +98,7 @@ export class NativeAgent {
     const request: ChatRequest = {
       messages: this.history,
       system: this.systemPrompt,
+      ...(this._thinking ? { thinking: true } : {}),
     };
 
     const response = await this.chatWithRouter(request);
@@ -101,10 +111,16 @@ export class NativeAgent {
       console.warn(`[Flynn] ${response.fallbackReason}`);
     }
 
+    // Prepend thinking content if present
+    let finalContent = response.content;
+    if (response.thinkingContent) {
+      finalContent = `<thinking>\n${response.thinkingContent}\n</thinking>\n\n${response.content}`;
+    }
+
     const assistantMsg: Message = { role: 'assistant', content: response.content };
     this.addToHistory(assistantMsg);
 
-    return response.content;
+    return finalContent;
   }
 
   private async toolLoop(): Promise<string> {
@@ -124,6 +140,7 @@ export class NativeAgent {
         messages: loopMessages as unknown as Message[],
         system: this.systemPrompt,
         tools,
+        ...(this._thinking ? { thinking: true } : {}),
       };
 
       const response = await this.chatWithRouter(request);
@@ -138,9 +155,13 @@ export class NativeAgent {
 
       // If the model didn't request tool use, we're done
       if (response.stopReason !== 'tool_use' || !response.toolCalls?.length) {
+        let finalContent = response.content;
+        if (response.thinkingContent) {
+          finalContent = `<thinking>\n${response.thinkingContent}\n</thinking>\n\n${response.content}`;
+        }
         const assistantMsg: Message = { role: 'assistant', content: response.content };
         this.addToHistory(assistantMsg);
-        return response.content;
+        return finalContent;
       }
 
       // Build the assistant message with tool_use content blocks