feat: add log-level system to suppress noisy fallback debug output

Replace console.debug/log/warn calls in model router, retry, and daemon
startup with a structured logger that respects a configurable log_level.
Default level is 'info', suppressing verbose fallback debug messages in
the TUI while keeping them available via config when needed.

- Add src/logger.ts with debug/info/warn/error/silent levels
- Wire log_level into config schema (default: 'info')
- Initialize log level in both daemon and TUI startup paths
- Convert all console.debug in router.ts and retry.ts to logger.debug
- Convert console.log/warn in daemon/models.ts to logger.info/warn

src/cli/tui.ts

@@ -4,6 +4,7 @@ import { loadConfigSafe, getConfigPath } from './shared.js';
 import { existsSync, mkdirSync, readFileSync } from 'fs';
 import { resolve } from 'path';
 import { homedir } from 'os';
+import { setLogLevel } from '../logger.js';
 
 // ANSI color codes for tool status display
 const toolColors = {
@@ -43,6 +44,8 @@ export function registerTuiCommand(program: Command): void {
 
       // Dynamic imports to keep CLI startup fast
       const { SessionStore, SessionManager } = await import('../session/index.js');
+
+      setLogLevel(config.log_level);
       const { MinimalTui, startFullscreenTui } = await import('../frontends/tui/index.js');
       const { NativeAgent } = await import('../backends/index.js');
       const { ToolRegistry, ToolExecutor, allBuiltinTools, createWebSearchTools, createProcessTools, ProcessManager } = await import('../tools/index.js');