feat(voice): per-account choice between Whisper and the browser; STT_ALLOW_BROWSER

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/storage/voice_input.go

@@ -0,0 +1,28 @@
+package storage
+
+import "errors"
+
+// Everyone picks how their voice input works: the server's Whisper ("", the default) or the browser's
+// recognition ("browser"). The server only offers the choice when it has a Whisper server and the
+// browser is allowed (STT_ALLOW_BROWSER); the app applies it (lib/voice.ts).
+
+var ErrInvalidVoiceInput = errors.New("Ungültige Spracheingabe (erlaubt: Whisper-Server oder Browser)")
+
+func (s *Store) migrateVoiceInput() error {
+	return s.addColumnIfMissing("users", "voice_input", "TEXT NOT NULL DEFAULT ''")
+}
+
+// VoiceInput returns the user's choice: "" or "browser".
+func (s *Store) VoiceInput(userID string) string {
+	var v string
+	_ = s.db.QueryRow(`SELECT voice_input FROM users WHERE id = ?`, userID).Scan(&v)
+	return v
+}
+
+func (s *Store) SetVoiceInput(userID, v string) error {
+	if v != "" && v != "browser" {
+		return ErrInvalidVoiceInput
+	}
+	_, err := s.db.Exec(`UPDATE users SET voice_input = ? WHERE id = ?`, v, userID)
+	return err
+}