feat: integrate model router, session persistence, and hook engine

- NativeAgent now loads/saves messages to SessionStore
- Daemon creates ModelRouter with fallback chain support
- Telegram bot handles confirmation callbacks from HookEngine
- Session data stored in ~/.local/share/flynn/sessions.db

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/backends/native/agent.ts

@@ -1,35 +1,60 @@
 import type { ModelClient, Message } from '../../models/types.js';
+import type { SessionStore } from '../../session/index.js';
 
 export interface NativeAgentConfig {
   modelClient: ModelClient;
   systemPrompt: string;
+  sessionStore?: SessionStore;
+  sessionId?: string;
 }
 
 export class NativeAgent {
   private modelClient: ModelClient;
   private systemPrompt: string;
+  private sessionStore?: SessionStore;
+  private sessionId: string;
   private history: Message[] = [];
 
   constructor(config: NativeAgentConfig) {
     this.modelClient = config.modelClient;
     this.systemPrompt = config.systemPrompt;
+    this.sessionStore = config.sessionStore;
+    this.sessionId = config.sessionId ?? 'default';
+
+    // Load existing history from store
+    if (this.sessionStore) {
+      this.history = this.sessionStore.getMessages(this.sessionId);
+    }
   }
 
   async process(userMessage: string): Promise<string> {
-    this.history.push({ role: 'user', content: userMessage });
+    const userMsg: Message = { role: 'user', content: userMessage };
+    this.history.push(userMsg);
+
+    if (this.sessionStore) {
+      this.sessionStore.addMessage(this.sessionId, userMsg);
+    }
 
     const response = await this.modelClient.chat({
       messages: [...this.history],
       system: this.systemPrompt,
     });
 
-    this.history.push({ role: 'assistant', content: response.content });
+    const assistantMsg: Message = { role: 'assistant', content: response.content };
+    this.history.push(assistantMsg);
+
+    if (this.sessionStore) {
+      this.sessionStore.addMessage(this.sessionId, assistantMsg);
+    }
 
     return response.content;
   }
 
   reset(): void {
     this.history = [];
+    if (this.sessionStore) {
+      this.sessionStore.clearSession(this.sessionId);
+    }
   }
 
   getHistory(): Message[] {