The Pretalx widget already persists favourites in localStorage under
'pycones-2026_favs' as a JSON array of session codes. This commit
mirrors that behaviour on the accessible list so users can bookmark
sessions in either view and have the preference stick.

UI:
- Heart icon button on every session card, pushed to the right of
  the metadata row
- aria-pressed for state, aria-label that flips between
  'Add to favourites' / 'Remove from favourites' based on state
- Visual state: outline heart (gray) when off, filled (orange) when on
- sr-only label 'Favourite' for screen readers

Script:
- Reads/writes the same 'pycones-2026_favs' key the widget uses
- Click handler: toggle, persist, update DOM
- 'storage' event listener: re-sync on cross-tab changes
- 'pycones:view-changed' custom event: re-sync when user switches
  to the list view (in case the widget mutated localStorage in
  the same session)

i18n:
- favorite, favoriteAdd, favoriteRemove (es/en/ca)

Two improvements to the favorite button accessibility:

1. Static label, state via aria-pressed only.
   The W3C ARIA Authoring Practices Guide recommends that toggle
   button labels stay stable across states. Screen reader users
   had been hearing a different label each time the button changed
   ('Add to favourites' → 'Remove from favourites'), which is more
   confusing than just 'Favourite, button, pressed/not pressed'.

2. Live region announces the result of the click.
   Previously the user clicked and got no audible confirmation. Now
   a polite live region says 'Added to favourites' / 'Removed from
   favourites' after each toggle. The text is cleared and re-set
   with a forced reflow so identical back-to-back messages still
   re-announce.

i18n: replaced favoriteAdd/favoriteRemove with favoriteAdded/
favoriteRemoved (past tense, used as announcement text).

…lose

The favorite button was being pushed to the far right of the full-width
viewport via ml-auto, which on desktop made it feel disconnected from
the rest of the session metadata.

Add max-w-3xl mx-auto to the schedule-list container so the day
headings and session cards stay within a comfortable reading width
(768px), keeping the heart visually close to the time/track info on
the same row.

A toggle button at the top of the list view that filters the
schedule to show only the user's bookmarked sessions.

- aria-pressed toggle button with heart icon
- Live count of favourites in the label
- CSS hides non-favourite <li> elements when the filter is active
  (via the is-favorite class added by syncFavorites on the <li>)
- Empty state: if the filter is on and there are 0 favourites,
  show a friendly message instead of a blank page
- i18n: favoritesOnly, noFavorites (es/en/ca)

Accessibility:
- The button itself is a proper toggle (aria-pressed, not a checkbox)
- The filter state is purely visual + local, no new localStorage key
  (the favourite list itself is already persisted)

…status

The 'Only favourites' filter button wasn't doing anything because two
click handlers were firing on each click:
1. The new event-delegation handler that toggles aria-pressed and
   the CSS class
2. The old direct listener (from the previous commit) that toggled
   aria-pressed again

Net effect: aria-pressed went true → false → true, leaving the
button exactly as it was. No visible change, no class added.

Fix: remove the old direct listener; the event-delegation handler
in the document click listener now owns both the per-session
favourite toggle and the filter toggle. Also refactored to share
a single announce() helper.

While here:
- Replace the buggy 'has-[:checked]:' Tailwind utilities (the button
  has no :checked state, it uses aria-pressed) with the correct
  'aria-pressed:' variants — those have proper specificity and
  the orange-pressed look now actually applies
- Add status announcements for the filter toggle via the existing
  #favorite-status live region: 'Favourites filter on. Showing N
  favourite session(s).' / 'Favourites filter off. Showing all
  sessions.'
- Decompose the i18n message into prefix + singular + plural words
  (filterOnPrefix, filterOnSingular, filterOnPlural, filterOff) so
  the script can build the count-aware message at runtime

Switch from event delegation to a direct click handler bound to the
button via getElementById. Adds try/catch + console.log statements
so we can see in the browser console whether the script is running,
the button is being found, and clicks are reaching the handler.

The button now has id='favorites-filter-btn' (was data-filter-favorites).
The script tries to bind the handler:
- immediately (in case the DOM is ready)
- on DOMContentLoaded (in case the script runs before DOM)
- on astro:page-load (in case the page is a view transition)
- guarded with dataset.bound so it only runs once

If the filter still doesn't work, the browser console will show
which of these steps is failing.

The previous attempt to fix the initial-load 'jump' by ignoring stale
localStorage values was too restrictive. The team wants the user's
choice to actually persist across visits.

New behavior:
- First visit (no saved value): default to visual grid
- After user picks list: save to localStorage, restore list on next visit
- After user picks grid: save to localStorage, restore grid on next visit

Legacy users who had 'list' saved from the old default will see a one-time
jump from grid → list on their first visit after this change. After that
they can click the grid radio to overwrite the saved value and stop the
jump.

Also cleaned up:
- Removed debug console.log statements left over from the filter fix
- Fixed a duplicated function body in the inline script that was
  breaking astro check

…scope

The 'only favourites' filter was toggling the button state and
adding the .filter-favorites-only class to the list view, but the
session cards were not being hidden. Reason: the CSS rule was in
ProgramaPage.astro and Astro's scoped styles injected
data-astro-cid-nm3rvpko into every selector, including .schedule-list
and li. But those elements are rendered by ScheduleList.astro which
has its own data-astro-cid-zmszfzov, so the selector never matched.

Fix: extract the filter CSS into an is:global block so the selector
reaches across the component boundary. Verified end-to-end with
Playwright:
- 0 favourites: 56/56 hidden (everything is filtered out)
- 1 favourite set: 1 visible, 55 hidden
- Toggle off: 56 visible again

Pre-paint script in <head> now sets data-schedule-view on <html>
before the first paint, so the saved view (list/grid) is applied
without a flash of the other view. When the URL has a session hash,
the view is forced to 'list' so the user lands directly on the
targeted session.

CSS now drives both view visibility and the visual highlight on the
view-mode toggle labels from the same data-schedule-view attribute,
so the active state matches the view on first paint. The radio's
hardcoded checked attribute is removed to avoid a visual mismatch
where grid would flash as active before the JS sync ran.

The favorites filter CSS was moved to Layout.astro's global styles
because the target <li> elements live in a child component
(ScheduleList) with a different Astro scope, which made the
previously-scoped rule unable to match.