feat: remove nginx, add projects/milestones/notifications pages

- Dockerfile: replace nginx with serve for static files
- Fix auth endpoint: /auth/login → /auth/token
- Add ProjectsPage, ProjectDetailPage
- Add MilestonesPage, MilestoneDetailPage with progress bar
- Add NotificationsPage with unread count
- Sidebar: add milestones/notifications nav, live unread badge
- API: configurable VITE_API_BASE for host nginx proxy
- Types: add Milestone, MilestoneProgress, Notification, ProjectMember

src/hooks/useAuth.ts

@@ -36,7 +36,9 @@ export function useAuth() {
     const form = new URLSearchParams()
     form.append('username', username)
     form.append('password', password)
-    const { data } = await api.post('/auth/login', form)
+    const { data } = await api.post('/auth/token', form, {
+      headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
+    })
     localStorage.setItem('token', data.access_token)
     setState((s) => ({ ...s, token: data.access_token }))
     await fetchUser()