Fix Characters tab: every selection errored, dropdown went stale

Real bug, not user error: Gradio refuses to serve a file back to the
browser unless it lives under the app's own directory, the system
temp dir, or an explicit allowlist. Every character's reference audio
lives in the-service-station repo, a completely different path, so
selecting *any* character in the Characters tab threw
gradio.exceptions.InvalidPathError server-side (visible in the server
log, not surfaced usefully in the browser's generic error toast).
Fixed with launch(allowed_paths=[SERVICE_STATION_DIR]), the documented
fix for this exact error.

Also: the character dropdowns choices were fixed at server-start time,
so a character created earlier in the same running session did not
show up without manually clicking Refresh. Added a demo.load() hook to
refresh both dropdowns automatically on page load, in addition to
keeping the manual Refresh button for mid-session use without a full
reload.

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Y1oQ4h4WE4R9KRvMQLr5Ey

webui/app.py

@@ -798,6 +798,22 @@ with gr.Blocks(title="Audio-demo pipeline studio") as demo:
                 inputs=[emotion_char_dd, emotion_word_tb, emotion_model_dd],
                 outputs=[emotion_ref_audio, emotion_preview_audio, emotion_status],
             )
+            # Dropdown choices are otherwise fixed at server-start time, so a
+            # character created earlier in the same running session (or by
+            # someone else) wouldn't show up without this - refresh
+            # automatically on every page load, in addition to the manual
+            # Refresh button above for mid-session use without reloading.
+            demo.load(
+                lambda: (gr.update(choices=character_names()), gr.update(choices=character_names())),
+                outputs=[char_dd, emotion_char_dd],
+            )
 
 if __name__ == "__main__":
-    demo.launch(server_name="0.0.0.0", server_port=7860)
+    # Gradio refuses to serve a file back to the browser unless it's under
+    # the app's own directory, the system temp dir, or explicitly allowed -
+    # every character's reference audio lives in the-service-station repo,
+    # a different path entirely, so every single Characters-tab selection
+    # errored without this (found via a real user report + the server log,
+    # not by inspection - the error only surfaces server-side, not in the
+    # browser's generic error toast).
+    demo.launch(server_name="0.0.0.0", server_port=7860, allowed_paths=[str(SERVICE_STATION_DIR)])