style(launcher): accessibility, session list UX, and preset-* token fixes

Style token fixes:
- launcher_cfg.svelte: tab buttons preset-filled-primary-500 -> preset-filled-primary;
  opacity-50 inactive -> preset-tonal-surface
- launcher_cfg_app_modes.svelte: same fix for app mode buttons (opacity-40)
- launcher_cfg_controller.svelte: variant-filled-success/error -> preset-filled-*
- launcher_cfg_template.svelte: variant-filled-success -> preset-filled-success
- launcher_session_view.svelte: add dark:border-gray-600/700 to bare border-gray-*

Session list (menu_session_list.svelte) -- full accessibility + UX pass:
- fix: background sync fetches hidden:all so All Sessions toggle works
- fix: hide_event_launcher respected in class:hidden and class:opacity-40
- fix: overlay uses explicit opaque backgrounds (slate-100/slate-800) to prevent
  preset-tonal-secondary transparency bleed-through in light and dark mode
- feat: compact fixed 2rem row height; position:absolute overlay on hover/focus
  reveals full session name (300-char) without any layout shift (no sibling movement)
- feat: active session always fully visible in flow (height:auto, no clipping)
- a11y: hover_timer_wait 750->1200ms (motor accessibility)
- a11y: removed hover:scale which caused cursor drift and timer jitter
- a11y: px-1.5 py-1 touch targets, focus-visible ring for keyboard/switch users
- a11y: fa-eye-slash icons distinguish hide vs hide_event_launcher states
- docs: comprehensive OSIT/Aether-specific comments throughout

src/routes/events/[event_id]/(launcher)/launcher_background_sync.svelte

@@ -148,6 +148,7 @@
                 for_obj_type: 'event_location',
                 for_obj_id: location_id,
                 view: 'alt',
+                hidden: 'all', // Launcher is operator-only; fetch all sessions so the "All Sessions" toggle works
                 try_cache: true,
                 log_lvl: 0
             });