* fix(settings): stop Test Dictation calling a missing model "no speech"
start_recognition now returns whether listening actually began. Test
Dictation checks that before starting its timer, so a missing or
auto-paused model gets a real error instead of "No speech detected".
* fix(settings): reconfigure Test Dictation against the live engine
UI matching config.json is not enough when speech_engine is still on
another engine or model size. Compare those too before the listen timer.
* fix(tests): keep settings_dialog lookups on one module
_load_settings_dialog() restored sys.modules but left
vocalinux.ui.settings_dialog pointing at the private reload.
Python 3.9/3.10 mock follows that attribute, so
test_whisper_list_and_delete patched a different copy than it
imported and the expanduser stub hid the real cache.
Point the package attribute back at the restored module, and
patch the imported module object in the deletion test.
Both modal download paths ran _apply_settings_internal() on a worker
thread and then unconditionally marked the progress dialog complete.
Since _apply_settings_internal() swallows every exception internally,
a download that failed or was cancelled still ended with "Complete!",
the dedicated except blocks below (the "Download cancelled" and
Whisper-not-installed branches) were unreachable, and the swallowed
path built and ran a Gtk.MessageDialog from the download thread, off
the main loop.
Give _apply_settings_internal() a raise_errors flag and pass it from
the two thread call sites. Their handlers become reachable and already
report through the progress dialog via GLib.idle_add, so failures now
surface with the real reason and no Gtk work happens off the main
loop. Main-loop callers keep the old contract: swallow, show the error
dialog, return False.
