Add core/modal.js with reusable Modal class that handles open/close,
body locking, backdrop close, dirty checking, error display, and a
static stack for ESC key management. Migrate all 13 modals across 8
feature files to use the base class, eliminating ~200 lines of
duplicated boilerplate. Replace manual ESC handler list in app.js
with Modal.closeTopmost(), fixing 3 modals that were previously
unreachable via ESC. Remove 5 unused initialValues variables from
state.js. Fix target editor to auto-select first device/source and
auto-generate name like the KC editor does.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
alexei.dolgolyov
ed220a97e7