feat(m11): calendar + milestones with progress calc, tests, e2e

- CalendarRepository (event CRUD, range query, soft-delete, project isolation)
  + MilestoneRepository (CRUD, findToDosByMilestone) + ScheduleService
  (aggregated getCalendarEvents = custom events+milestones+todos in range,
  milestone CRUD, milestone_updated activity, progress auto-calc 0-100)
- APIs: calendar events GET/POST/PATCH/DELETE, milestones GET/POST/PATCH +
  progress
- Screens: calendar list view + CalendarEventForm, milestones list with
  progress bars + MilestoneForm, ProjectNav links
- Unit tests (CalendarRepository, MilestoneRepository, ScheduleService incl.
  progress calc 0/33/100) + e2e calendar

app/api/projects/[projectId]/calendar/events/route.ts

@@ -0,0 +1,56 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { getCurrentUser } from '@/lib/auth/getCurrentUser';
+import { createScheduleService } from '@/lib/api/services';
+import { UnauthorizedError } from '@/lib/errors';
+import { handleApiError, jsonError } from '@/lib/api/handleError';
+
+export const runtime = 'nodejs';
+
+export async function GET(
+  request: NextRequest,
+  { params }: { params: Promise<{ projectId: string }> }
+) {
+  const user = await getCurrentUser();
+  if (!user) return handleApiError(new UnauthorizedError());
+  const { projectId } = await params;
+  const from = request.nextUrl.searchParams.get('from') ?? '';
+  const to = request.nextUrl.searchParams.get('to') ?? '';
+  const service = createScheduleService();
+  try {
+    return NextResponse.json(
+      service.getCalendarEvents(user.id, Number(projectId), { from, to })
+    );
+  } catch (error) {
+    return handleApiError(error);
+  }
+}
+
+export async function POST(
+  request: NextRequest,
+  { params }: { params: Promise<{ projectId: string }> }
+) {
+  const user = await getCurrentUser();
+  if (!user) return handleApiError(new UnauthorizedError());
+  const { projectId } = await params;
+  let body: Record<string, unknown>;
+  try {
+    body = (await request.json()) as Record<string, unknown>;
+  } catch {
+    return jsonError(400, 'リクエスト本文が不正です');
+  }
+  const service = createScheduleService();
+  try {
+    const event = service.createEvent(user.id, {
+      projectId: Number(projectId),
+      title: String(body.title ?? ''),
+      type: (typeof body.type === 'string' ? body.type : 'custom') as never,
+      startAt: String(body.startAt ?? ''),
+      endAt: typeof body.endAt === 'string' ? body.endAt : null,
+      description:
+        typeof body.description === 'string' ? body.description : null,
+    });
+    return NextResponse.json({ event }, { status: 201 });
+  } catch (error) {
+    return handleApiError(error);
+  }
+}