feat: align docs with code, finish_place, registered status, UI filters, tests, CI

- Add PLAN.md and sync backend docs, .env.example, API doc (404 details)
- Document mock DB and PORT/API_PORT in docs/backend.md; README monorepo + frontend/.env.example
- Migration 002: finish_place column, status registered; mapper and mock DB updated
- Frontend: registered status, finishPlace, calendar year/month filters, pace sparkline
- Extract createApp for tests; supertest + tsx; GitHub Actions CI

Made-with: Cursor

frontend/src/api/races.ts

@@ -18,13 +18,17 @@ function normalizeRace(input: unknown): Race {
     isString(race?.date) &&
     isString(race?.title) &&
     typeof race?.distanceKm === "number" &&
-    (race?.status === null || race?.status === "planned" || race?.status === "completed") &&
+    (race?.status === null ||
+      race?.status === "planned" ||
+      race?.status === "registered" ||
+      race?.status === "completed") &&
     isNullableString(race?.officialUrl) &&
     isNullableString(race?.startTime) &&
     isNullableString(race?.clusterSchedule) &&
     isNullableString(race?.bibPickup) &&
     isNullableString(race?.bibNumber) &&
     isNullableString(race?.finishTime) &&
+    isNullableString(race?.finishPlace) &&
     isNullableString(race?.notes) &&
     isString(race?.createdAt) &&
     (race?.updatedAt === null || isString(race?.updatedAt));
@@ -49,6 +53,7 @@ function normalizeRace(input: unknown): Race {
     bibPickup: race.bibPickup,
     bibNumber: race.bibNumber,
     finishTime: race.finishTime,
+    finishPlace: race.finishPlace,
     notes: race.notes,
     createdAt: race.createdAt,
     updatedAt: race.updatedAt,