feat: Add metadata table for internal state storage

The other agent added a metadata table for storing internal state
like import hashes. This is separate from the config table which
is for user-facing configuration.

🤖 Generated by other agent

internal/storage/sqlite/schema.go

@@ -72,6 +72,12 @@ CREATE TABLE IF NOT EXISTS config (
     value TEXT NOT NULL
 );
 
+-- Metadata table (for storing internal state like import hashes)
+CREATE TABLE IF NOT EXISTS metadata (
+    key TEXT PRIMARY KEY,
+    value TEXT NOT NULL
+);
+
 -- Dirty issues table (for incremental JSONL export)
 -- Tracks which issues have changed since last export
 CREATE TABLE IF NOT EXISTS dirty_issues (

internal/storage/sqlite/sqlite.go

@@ -662,6 +662,25 @@ func (s *SQLiteStorage) GetConfig(ctx context.Context, key string) (string, erro
 	return value, err
 }
 
+// SetMetadata sets a metadata value (for internal state like import hashes)
+func (s *SQLiteStorage) SetMetadata(ctx context.Context, key, value string) error {
+	_, err := s.db.ExecContext(ctx, `
+		INSERT INTO metadata (key, value) VALUES (?, ?)
+		ON CONFLICT (key) DO UPDATE SET value = excluded.value
+	`, key, value)
+	return err
+}
+
+// GetMetadata gets a metadata value (for internal state like import hashes)
+func (s *SQLiteStorage) GetMetadata(ctx context.Context, key string) (string, error) {
+	var value string
+	err := s.db.QueryRowContext(ctx, `SELECT value FROM metadata WHERE key = ?`, key).Scan(&value)
+	if err == sql.ErrNoRows {
+		return "", nil
+	}
+	return value, err
+}
+
 // Close closes the database connection
 func (s *SQLiteStorage) Close() error {
 	return s.db.Close()

internal/storage/storage.go

@@ -52,6 +52,10 @@ type Storage interface {
 	SetConfig(ctx context.Context, key, value string) error
 	GetConfig(ctx context.Context, key string) (string, error)
 
+	// Metadata (for internal state like import hashes)
+	SetMetadata(ctx context.Context, key, value string) error
+	GetMetadata(ctx context.Context, key string) (string, error)
+
 	// Lifecycle
 	Close() error
 }