Add backend foundation and config-driven workbench

backend/migrations/0004_results.sql

@@ -0,0 +1,26 @@
+BEGIN;
+
+CREATE TABLE session_results (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  session_id UUID NOT NULL UNIQUE REFERENCES game_sessions(id) ON DELETE CASCADE,
+  result_status TEXT NOT NULL CHECK (result_status IN ('finished', 'failed', 'cancelled')),
+  summary_jsonb JSONB NOT NULL DEFAULT '{}'::jsonb,
+  final_duration_sec INTEGER,
+  final_score INTEGER,
+  completed_controls INTEGER,
+  total_controls INTEGER,
+  distance_meters NUMERIC(10,2),
+  average_speed_kmh NUMERIC(8,3),
+  max_heart_rate_bpm INTEGER,
+  created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+  updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX session_results_result_status_idx ON session_results(result_status);
+CREATE INDEX session_results_created_at_idx ON session_results(created_at DESC);
+
+CREATE TRIGGER session_results_set_updated_at
+BEFORE UPDATE ON session_results
+FOR EACH ROW EXECUTE FUNCTION set_updated_at();
+
+COMMIT;