FE-PR-001: Rename Propose -> Proposal across frontend

- Rename ProposesPage -> ProposalsPage, ProposeDetailPage -> ProposalDetailPage
- Update Propose type to Proposal (keep Propose as deprecated alias)
- Add GeneratedTask type for accept results
- Switch API calls from /proposes to /proposals (canonical)
- Update sidebar label: Proposes -> Proposals
- Update routes: /proposals (+ legacy /proposes compat)
- Update all UI text: Propose -> Proposal
- Remove feat_task_id display, add generated_tasks section
- Clean up propose references in comments

src/App.tsx

@@ -14,8 +14,8 @@ import MilestoneDetailPage from '@/pages/MilestoneDetailPage'
 import NotificationsPage from '@/pages/NotificationsPage'
 import RoleEditorPage from '@/pages/RoleEditorPage'
 import MonitorPage from '@/pages/MonitorPage'
-import ProposesPage from '@/pages/ProposesPage'
-import ProposeDetailPage from '@/pages/ProposeDetailPage'
+import ProposalsPage from '@/pages/ProposalsPage'
+import ProposalDetailPage from '@/pages/ProposalDetailPage'
 import UsersPage from '@/pages/UsersPage'
 import SupportDetailPage from '@/pages/SupportDetailPage'
 import MeetingDetailPage from '@/pages/MeetingDetailPage'
@@ -116,8 +116,11 @@ export default function App() {
             <Route path="/projects/:id" element={<ProjectDetailPage />} />
             <Route path="/milestones" element={<MilestonesPage />} />
             <Route path="/milestones/:id" element={<MilestoneDetailPage />} />
-            <Route path="/proposes" element={<ProposesPage />} />
-            <Route path="/proposes/:id" element={<ProposeDetailPage />} />
+            <Route path="/proposals" element={<ProposalsPage />} />
+            <Route path="/proposals/:id" element={<ProposalDetailPage />} />
+            {/* Legacy routes for backward compatibility */}
+            <Route path="/proposes" element={<ProposalsPage />} />
+            <Route path="/proposes/:id" element={<ProposalDetailPage />} />
             <Route path="/meetings/:meetingId" element={<MeetingDetailPage />} />
             <Route path="/supports/:supportId" element={<SupportDetailPage />} />
             <Route path="/notifications" element={<NotificationsPage />} />