Initial commit: smartrun MVP

Garmin run classification and progression tracker. Go backend (MCP
client to mcp-garmin, SQLite store, deterministic rule engine, REST
API) and React/TS frontend (Dashboard, Review Queue, Workout Kinds).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/internal/store/syncstate_test.go

@@ -0,0 +1,31 @@
+package store
+
+import (
+	"context"
+	"testing"
+)
+
+func TestSyncState_DefaultsAndUpdate(t *testing.T) {
+	db := openTestDB(t)
+	ctx := context.Background()
+
+	state, err := db.GetSyncState(ctx)
+	if err != nil {
+		t.Fatalf("GetSyncState: %v", err)
+	}
+	if state.EarliestSyncedDate != nil || state.BackfillComplete {
+		t.Fatalf("expected fresh DB to have no watermark, got %+v", state)
+	}
+
+	if err := db.UpdateSyncState(ctx, "2023-01-01", true); err != nil {
+		t.Fatalf("UpdateSyncState: %v", err)
+	}
+
+	state, err = db.GetSyncState(ctx)
+	if err != nil {
+		t.Fatalf("GetSyncState after update: %v", err)
+	}
+	if state.EarliestSyncedDate == nil || *state.EarliestSyncedDate != "2023-01-01" || !state.BackfillComplete {
+		t.Fatalf("state after update = %+v, want earliest=2023-01-01 complete=true", state)
+	}
+}