Add settings.html (shell + sub-tab nav + conditional list/edit body),
notifications.html and notification_edit.html (glob stubs), and the
supporting CSS tokens (.ch-row, .ch-icon, .toggle, .kind-grid,
.kind-card, .radio-pip, .test-pill) to input.css. Rebuild styles.css.
Add ui_parse_test.go to catch template regressions at test time.
The kind picker is JS-driven (no full page reload); the enabled toggle
mirrors the existing visual toggle pattern; the test-notification button
uses HTMX and renders the JSON response as a coloured pill client-side.
