feat: complete i18n translation for remaining components

- Translate pages: Projects, ProjectHealthPage, ProjectSettings
- Translate components: TaskDetailModal, KanbanBoard, Comments,
  SubtaskList, CalendarView, BlockerDialog
- Add translation keys for tasks namespace: kanban, calendar,
  subtasks.error, comments.error, blockers (full translation)
- Add common.labels.task translation key
- Fix task creation: use original_estimate instead of time_estimate

Translation coverage:
- 10 locale files updated (zh-TW & en)
- 6 page/component files translated
- ~100 new translation keys added

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

frontend/public/locales/en/health.json

@@ -1,12 +1,29 @@
 {
-  "title": "Project Health",
-  "subtitle": "Monitor the overall health of projects",
+  "title": "Project Health Dashboard",
+  "subtitle": "Monitor project health status and risk levels across all projects",
   "overall": {
     "title": "Overall Health",
     "healthy": "Healthy",
     "atRisk": "At Risk",
     "critical": "Critical"
   },
+  "summary": {
+    "totalProjects": "Total Projects",
+    "healthy": "Healthy",
+    "atRisk": "At Risk",
+    "critical": "Critical",
+    "avgHealth": "Avg. Health",
+    "withBlockers": "With Blockers",
+    "delayed": "Delayed"
+  },
+  "sort": {
+    "label": "Sort by",
+    "riskHigh": "Risk: High to Low",
+    "riskLow": "Risk: Low to High",
+    "healthHigh": "Health: High to Low",
+    "healthLow": "Health: Low to High",
+    "name": "Name: A to Z"
+  },
   "metrics": {
     "schedule": "Schedule",
     "budget": "Budget",
@@ -34,15 +51,21 @@
     "high": "High Risk",
     "medium": "Medium Risk",
     "low": "Low Risk",
+    "critical": "Critical",
     "mitigated": "Mitigated"
   },
   "actions": {
     "viewDetails": "View Details",
     "exportReport": "Export Report",
-    "setAlert": "Set Alert"
+    "setAlert": "Set Alert",
+    "retry": "Retry"
   },
+  "projectCount": "{{count}} project(s)",
   "empty": {
-    "title": "No Health Data",
-    "description": "The project needs more data to display health metrics"
+    "title": "No projects found",
+    "description": "Create a project to start tracking health status"
+  },
+  "error": {
+    "loadFailed": "Failed to load project health data. Please try again."
   }
 }