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/daemon/models.ts

@@ -1,6 +1,7 @@
 import type { Config, ModelConfig } from '../config/index.js';
 import { AnthropicClient, OpenAIClient, OllamaClient, LlamaCppClient, GeminiClient, BedrockClient, GitHubModelsClient, ModelRouter, DEFAULT_RETRY_CONFIG } from '../models/index.js';
 import type { ModelClient, RetryConfig, ModelTier } from '../models/index.js';
+import { logger } from '../logger.js';
 
 /**
  * Create a ModelClient from a provider config entry.
@@ -166,7 +167,7 @@ export function createModelRouter(config: Config): ModelRouter {
       // Named provider from local_providers map
       fallbackChain.push(createClientFromConfig(models.local_providers[providerName]));
     } else {
-      console.warn(`Fallback chain entry "${providerName}" not found — skipping`);
+      logger.warn(`Fallback chain entry "${providerName}" not found — skipping`);
     }
   }
 
@@ -211,13 +212,13 @@ export function createModelRouter(config: Config): ModelRouter {
 
   if (tierFallbacks.size > 0) {
     const tierNames = Array.from(tierFallbacks.keys()).join(', ');
-    console.log(`Per-tier fallbacks configured for: ${tierNames}`);
+    logger.info(`Per-tier fallbacks configured for: ${tierNames}`);
   }
   if (autoFallbackTiers.length > 0) {
-    console.log(`Auto same-model fallback (via GitHub Models) for: ${autoFallbackTiers.join(', ')}`);
+    logger.info(`Auto same-model fallback (via GitHub Models) for: ${autoFallbackTiers.join(', ')}`);
   }
 
-  console.log(`Model router: default=${models.default.provider}/${models.default.model}, ` +
+  logger.info(`Model router: default=${models.default.provider}/${models.default.model}, ` +
     `fallback=[${models.fallback_chain.join(', ')}]`);
 
   // Build retry config if enabled
@@ -230,7 +231,7 @@ export function createModelRouter(config: Config): ModelRouter {
   } : undefined;
 
   if (retryConfig) {
-    console.log(`Retry policy: max_retries=${retryConfig.maxRetries}, initial_delay=${retryConfig.initialDelayMs}ms`);
+    logger.info(`Retry policy: max_retries=${retryConfig.maxRetries}, initial_delay=${retryConfig.initialDelayMs}ms`);
   }
 
   return new ModelRouter({