filter_template references were silently ignored in PP template test,
picture source test, and KC target test routes — they created a no-op
FilterTemplateFilter instead of expanding into the referenced template's
filters. Centralized expansion logic into PostprocessingTemplateStore.
resolve_filter_instances() and use it in all test routes + live stream
manager.
Also fixed empty template_id when adding filter_template filters: the
select dropdown showed the first template visually but onchange never
fired, saving "" instead. Now initializes with first choice's value and
auto-corrects stale/empty values at render time.
Other fixes: ScreenCapture dimensions now use actual image shape after
filter processing; brightness source label emoji updates.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add new "audio" color strip source type with three visualization modes
(spectrum analyzer, beat pulse, VU meter) supporting WASAPI loopback and
microphone input via PyAudioWPatch. Includes shared audio capture with
ref counting, real-time FFT spectrum analysis, and beat detection.
Improve all referential integrity 409 error messages across delete
endpoints to include specific names of referencing entities instead of
generic "one or more" messages.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
