feat: implement soft delete, task editing fixes, and UI improvements

Backend:
- Add soft delete for spaces and projects (is_active flag)
- Add status_id and assignee_id to TaskUpdate schema
- Fix task PATCH endpoint to update status and assignee
- Add validation for assignee_id and status_id in task updates
- Fix health service to count tasks with "Blocked" status as blockers
- Filter out deleted spaces/projects from health dashboard
- Add workload cache invalidation on assignee changes

Frontend:
- Add delete confirmation dialogs for spaces and projects
- Fix UserSelect to display selected user name (valueName prop)
- Fix task detail modal to refresh data after save
- Enforce 2-level subtask depth limit in UI
- Fix timezone bug in date formatting (use local timezone)
- Convert NotificationBell from Tailwind to inline styles
- Add i18n translations for health, workload, settings pages
- Add parent_task_id to Task interface across components

OpenSpec:
- Archive add-delete-capability change

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

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

frontend/public/locales/zh-TW/health.json

@@ -11,11 +11,24 @@
     "totalProjects": "專案總數",
     "healthy": "健康",
     "atRisk": "風險中",
+    "highRisk": "高風險",
     "critical": "危急",
     "avgHealth": "平均健康度",
     "withBlockers": "有阻擋問題",
     "delayed": "延遲"
   },
+  "calculation": {
+    "title": "健康度計算方式",
+    "formula": "起始分數 100 分，依據以下因素扣分：",
+    "blockers": "阻擋問題：每項 -10 分（最多 -30 分）",
+    "overdue": "逾期任務：每項 -5 分（最多 -30 分）",
+    "completion": "完成度不足：若低於 50%，最多 -20 分",
+    "thresholds": "風險等級閾值：",
+    "lowRisk": "低風險（健康）：≥ 80 分",
+    "mediumRisk": "中風險：60-79 分",
+    "highRiskLevel": "高風險：40-59 分",
+    "criticalRisk": "危急：< 40 分"
+  },
   "sort": {
     "label": "排序方式",
     "riskHigh": "風險：高到低",
@@ -36,7 +49,29 @@
     "delayed": "延遲",
     "ahead": "超前",
     "overBudget": "超支",
-    "underBudget": "低於預算"
+    "underBudget": "低於預算",
+    "atRisk": "有風險"
+  },
+  "resourceStatus": {
+    "adequate": "充足",
+    "constrained": "受限",
+    "overloaded": "超載"
+  },
+  "card": {
+    "health": "健康度",
+    "schedule": "進度",
+    "resources": "資源",
+    "owner": "負責人",
+    "taskProgress": "任務進度",
+    "blockers": "阻擋問題",
+    "overdue": "逾期",
+    "complete": "完成"
+  },
+  "riskLevel": {
+    "low": "低風險",
+    "medium": "中風險",
+    "high": "高風險",
+    "critical": "危急"
   },
   "indicators": {
     "title": "健康指標",