Add leaderboard for all tracks and track calendar

server/internal/storage/postgres/migrations/014_track_calendar.sql

@@ -0,0 +1,11 @@
+-- 014_track_calendar.sql — schema for F1-style active track scheduling.
+
+CREATE TABLE IF NOT EXISTS track_calendar (
+    id SERIAL PRIMARY KEY,
+    track_id TEXT NOT NULL REFERENCES tracks(id) ON DELETE CASCADE,
+    start_at TIMESTAMP WITH TIME ZONE NOT NULL,
+    end_at TIMESTAMP WITH TIME ZONE NOT NULL,
+    CHECK (start_at < end_at)
+);
+
+CREATE INDEX IF NOT EXISTS track_calendar_dates_idx ON track_calendar (start_at, end_at);