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/public/locales/en/audit.json

@@ -52,5 +52,39 @@
   "empty": {
     "title": "No Audit Records",
     "description": "No audit records match the current filters"
+  },
+  "modal": {
+    "details": {
+      "title": "Audit Log Details",
+      "eventType": "Event Type:",
+      "action": "Action:",
+      "resource": "Resource:",
+      "user": "User:",
+      "ipAddress": "IP Address:",
+      "sensitivity": "Sensitivity:",
+      "time": "Time:",
+      "changes": "Changes",
+      "field": "Field",
+      "oldValue": "Old Value",
+      "newValue": "New Value",
+      "checksum": "Checksum:",
+      "na": "N/A",
+      "system": "System"
+    },
+    "verification": {
+      "title": "Integrity Verification",
+      "verifying": "Verifying audit log integrity...",
+      "verifyingHint": "This may take a moment depending on the number of records.",
+      "failed": "Verification Failed",
+      "statusSuccess": "Integrity Verified",
+      "statusFailed": "Integrity Issues Detected",
+      "successDescription": "All audit records have valid checksums and have not been tampered with.",
+      "failedDescription": "Some audit records have invalid checksums, indicating potential tampering or corruption.",
+      "totalChecked": "Total Checked",
+      "valid": "Valid",
+      "invalid": "Invalid",
+      "invalidRecords": "Invalid Records",
+      "invalidRecordsDescription": "The following record IDs failed integrity verification:"
+    }
   }
 }