Fix :memory: database connection pool issue (bd-b121)

- Add db.SetMaxOpenConns(1) for :memory: databases
- SQLite shared cache mode requires single connection
- Fixes 'no such table' errors in VC and other consumers
- See bd-b121 for full details

Amp-Thread-ID: https://ampcode.com/threads/T-bbbb8f17-5ac0-4125-9035-e5488d3ebab1
Co-authored-by: Amp <amp@ampcode.com>

internal/storage/sqlite/sqlite.go

@@ -48,6 +48,13 @@ func New(path string) (*SQLiteStorage, error) {
 		return nil, fmt.Errorf("failed to open database: %w", err)
 	}
 
+	// For :memory: databases, force single connection to ensure cache sharing works properly.
+	// SQLite's shared cache mode for in-memory databases only works reliably with one connection.
+	// Without this, different connections in the pool can't see each other's writes (bd-b121).
+	if path == ":memory:" {
+		db.SetMaxOpenConns(1)
+	}
+
 	// Test connection
 	if err := db.Ping(); err != nil {
 		return nil, fmt.Errorf("failed to ping database: %w", err)