Add SQLite persistence, import-snapshot tool, and karma functionality

server/internal/store/sqlite/store.go

@@ -0,0 +1,25 @@
+package sqlite
+
+import (
+	"database/sql"
+	"time"
+
+	"lunar-tear/server/internal/store"
+)
+
+type SQLiteStore struct {
+	db    *sql.DB
+	clock store.Clock
+}
+
+var (
+	_ store.UserRepository    = (*SQLiteStore)(nil)
+	_ store.SessionRepository = (*SQLiteStore)(nil)
+)
+
+func New(db *sql.DB, clock store.Clock) *SQLiteStore {
+	if clock == nil {
+		clock = time.Now
+	}
+	return &SQLiteStore{db: db, clock: clock}
+}