feat: implement debug logging cleanup and i18n coverage proposals

## cleanup-debug-logging
- Create environment-aware logger utility (logger.ts)
- Replace 60+ console.log/error statements across 28 files
- Production: only warn/error logs visible
- Development: all log levels with prefixes

Updated files:
- Contexts: NotificationContext, ProjectSyncContext, AuthContext
- Components: GanttChart, CalendarView, ErrorBoundary, and 11 others
- Pages: Tasks, Projects, Dashboard, and 7 others
- Services: api.ts

## complete-i18n-coverage
- WeeklyReportPreview: all strings translated, dynamic locale
- ReportHistory: all strings translated, dynamic locale
- AuditPage: detail modal and verification modal translated
- WorkloadPage: error message translated

Locale files updated:
- en/common.json, zh-TW/common.json: reports section
- en/audit.json, zh-TW/audit.json: modal sections
- en/workload.json, zh-TW/workload.json: errors section

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

frontend/src/components/ResourceHistory.tsx

@@ -1,5 +1,6 @@
 import { useState, useEffect, useCallback } from 'react'
 import { auditService, AuditLog } from '../services/audit'
+import { logger } from '../utils/logger'
 
 interface ResourceHistoryProps {
   resourceType: string
@@ -18,7 +19,7 @@ export function ResourceHistory({ resourceType, resourceId, title = 'Change Hist
       const response = await auditService.getResourceHistory(resourceType, resourceId, 10)
       setLogs(response.logs)
     } catch (error) {
-      console.error('Failed to load resource history:', error)
+      logger.error('Failed to load resource history:', error)
     } finally {
       setLoading(false)
     }