feat(core): migrate console calls to debugLogger (M3 Phase 6)

Migrate remaining console.* calls in packages/core utilities and services
to use the structured DebugLogger pattern. This continues the Phase 6
migration work for utilities and helpers.

Files migrated:
- config/config.ts, core/client.ts, core/prompts.ts
- core/anthropicContentGenerator, core/openaiContentGenerator
- core/coreToolScheduler.ts, fallback/handler.ts
- models/modelRegistry.ts, prompts/prompt-registry.ts
- services/chatRecordingService.ts, sessionService.ts, loopDetectionService.ts
- skills/skill-load.ts, skill-manager.ts
- subagents/subagent.ts, subagent-manager.ts
- utils: editor, environmentContext, fileUtils, getFolderStructure,
  installationManager, jsonl-utils, llm-edit-fixer, nextSpeakerChecker,
  openaiLogger, request-tokenizer/*, retry, ripgrepUtils, safeJsonParse,
  summarizer, systemEncoding, workspaceContext

Remaining: utils/errorReporting.ts (13 calls)

packages/core/src/skills/skill-load.ts

@@ -2,6 +2,9 @@ import type { SkillConfig, SkillValidationResult } from './types.js';
 import * as fs from 'fs/promises';
 import * as path from 'path';
 import { parse as parseYaml } from '../utils/yaml-parser.js';
+import { createDebugLogger } from '../utils/debugLogger.js';
+
+const debugLogger = createDebugLogger('SKILL_LOAD');
 
 const SKILL_MANIFEST_FILE = 'SKILL.md';
 
@@ -26,7 +29,7 @@ export async function loadSkillsFromDir(
         const config = parseSkillContent(content, skillManifest);
         skills.push(config);
       } catch (error) {
-        console.warn(
+        debugLogger.warn(
           `Failed to parse skill at ${skillDir}: ${error instanceof Error ? error.message : 'Unknown error'}`,
         );
         continue;

packages/core/src/skills/skill-manager.ts

@@ -19,6 +19,9 @@ import type {
 import { SkillError, SkillErrorCode } from './types.js';
 import type { Config } from '../config/config.js';
 import { validateConfig } from './skill-load.js';
+import { createDebugLogger } from '../utils/debugLogger.js';
+
+const debugLogger = createDebugLogger('SKILL_MANAGER');
 
 const QWEN_CONFIG_DIR = '.qwen';
 const SKILLS_CONFIG_DIR = 'skills';
@@ -57,7 +60,7 @@ export class SkillManager {
       try {
         listener();
       } catch (error) {
-        console.warn('Skill change listener threw an error:', error);
+        debugLogger.warn('Skill change listener threw an error:', error);
       }
     }
   }
@@ -214,7 +217,7 @@ export class SkillManager {
   stopWatching(): void {
     for (const watcher of this.watchers.values()) {
       void watcher.close().catch((error) => {
-        console.warn('Failed to close skills watcher:', error);
+        debugLogger.warn('Failed to close skills watcher:', error);
       });
     }
     this.watchers.clear();
@@ -426,7 +429,7 @@ export class SkillManager {
           // Skip directories without valid SKILL.md
           if (error instanceof SkillError) {
             // Parse error was already recorded
-            console.warn(
+            debugLogger.warn(
               `Failed to parse skill at ${skillDir}: ${error.message}`,
             );
           }
@@ -486,7 +489,7 @@ export class SkillManager {
           .get(existingPath)
           ?.close()
           .catch((error) => {
-            console.warn(
+            debugLogger.warn(
               `Failed to close skills watcher for ${existingPath}:`,
               error,
             );
@@ -508,11 +511,11 @@ export class SkillManager {
             this.scheduleRefresh();
           })
           .on('error', (error) => {
-            console.warn(`Skills watcher error for ${watchPath}:`, error);
+            debugLogger.warn(`Skills watcher error for ${watchPath}:`, error);
           });
         this.watchers.set(watchPath, watcher);
       } catch (error) {
-        console.warn(
+        debugLogger.warn(
           `Failed to watch skills directory at ${watchPath}:`,
           error,
         );
@@ -536,7 +539,7 @@ export class SkillManager {
     try {
       await fs.mkdir(baseDir, { recursive: true });
     } catch (error) {
-      console.warn(
+      debugLogger.warn(
         `Failed to create user skills directory at ${baseDir}:`,
         error,
       );