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

backend/src/mappers/race.ts

@@ -11,6 +11,7 @@ export interface RaceRow {
   bib_pickup: string | null;
   bib_number: string | null;
   finish_time: string | null;
+  finish_place: string | null;
   notes: string | null;
   created_at: string;
   updated_at: string | null;
@@ -29,6 +30,7 @@ export interface RaceDto {
   bibPickup: string | null;
   bibNumber: string | null;
   finishTime: string | null;
+  finishPlace: string | null;
   notes: string | null;
   createdAt: string;
   updatedAt: string | null;
@@ -48,6 +50,7 @@ export function rowToDto(row: RaceRow): RaceDto {
     bibPickup: row.bib_pickup,
     bibNumber: row.bib_number,
     finishTime: row.finish_time,
+    finishPlace: row.finish_place,
     notes: row.notes,
     createdAt: row.created_at,
     updatedAt: row.updated_at,
@@ -66,6 +69,7 @@ const FIELD_MAP: Record<string, string> = {
   bibPickup: "bib_pickup",
   bibNumber: "bib_number",
   finishTime: "finish_time",
+  finishPlace: "finish_place",
   notes: "notes",
 };