Accessibility audit (WCAG 2.2)

This issue tracks the results of a WCAG 2.2 accessibility audit of civictech.ca.

## What's already working well

- Skip link (`#main-content`) with correct CSS reveal-on-focus behaviour
- ``, semantic HTML5 landmarks throughout
- `aria-label="breadcrumb"` on every content layout's breadcrumb nav
- Mobile menu has `aria-expanded`, `aria-controls`, `aria-label` on toggle/close buttons
- `hidden` DOM attribute (not just CSS) used to genuinely hide mobile menu from AT
- Feedback form uses ``/``, properly associated labels, `role="alert"` on error/success messages
- Logo SVG has `aria-hidden="true"` with visible text following it
- Dark mode respects `prefers-color-scheme`
- External link `↗` arrows wrapped in `aria-hidden="true"` in most locations

## Issues to fix

Sub-issues are grouped by severity below. See each linked issue for full details and affected file locations.

### Critical

- [ ] Add `alt` attributes to project images
- [ ] Remove `outline: none` focus suppression in feedback form
- [ ] Hidden feedback form sections remain reachable by screen readers
- [ ] Mobile menu has no focus management on open/close

### Serious

- [ ] Icon SVGs missing `aria-hidden` / inconsistent accessible names
- [ ] YouTube embed title is non-descriptive
- [ ] `` is invalid HTML on About Us speaker links
- [ ] Footer theme-switcher `` has no `aria-label`
- [ ] Desktop nav uses `` instead of `` for navigation
- [ ] Modal dialog has no focus trap

- [ ] No `aria-current="page"` on active nav items
- [ ] Announcement bar has no landmark role or `aria-live`
- [ ] No `prefers-reduced-motion` CSS support