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

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

internal/config/config_test.go

@@ -120,3 +120,24 @@ func TestCustomLinkValidation(t *testing.T) {
 		t.Errorf("expected empty custom link when url is empty, got url=%q label=%q", cfg.Legal.CustomLinkURL, cfg.Legal.CustomLinkLabel)
 	}
 }
+
+// STT_ALLOW_BROWSER=false: without a Whisper server (or in the demo) there is no voice input at all
+func TestSpeechModeWithoutBrowser(t *testing.T) {
+	cases := []struct {
+		cfg  SpeechConfig
+		demo bool
+		want string
+	}{
+		{SpeechConfig{URL: "http://whisper:8000"}, false, "server"},
+		{SpeechConfig{URL: "http://whisper:8000", NoBrowser: true}, false, "server"},
+		{SpeechConfig{}, false, "browser"},
+		{SpeechConfig{NoBrowser: true}, false, "off"},
+		{SpeechConfig{URL: "http://whisper:8000", NoBrowser: true}, true, "off"},
+		{SpeechConfig{URL: "http://whisper:8000", Disabled: true}, false, "off"},
+	}
+	for _, c := range cases {
+		if got := c.cfg.Mode(c.demo); got != c.want {
+			t.Errorf("%+v demo=%v: got %q, want %q", c.cfg, c.demo, got, c.want)
+		}
+	}
+}