New Photos section reachable from Agenda's overflow menu: reuses
FilesRepository's WebDAV browsing (folders + image-filtered files) in
a grid, with a swipeable full-screen viewer (HorizontalPager) on tap.
Thumbnails/full images load via Coil with a custom OkHttpClient that
injects the same Basic Auth used everywhere else - no new network
client needed, just two small synchronous accessors added to
FilesRepository (rawFileUrl/basicAuthHeader) since Coil needs a plain
URL + header rather than a suspend call.
Also moved Talk/Files/Photos/Calendars into an overflow menu on
Agenda's top bar - it had grown to 7 icons across this session and
the title had started wrapping to two lines.
Real bug found and fixed live: the photo viewer's close button was
completely untappable (visually present, but taps never registered).
Root cause was the same class of issue as an earlier Snackbar gotcha
this session - MainActivity calls enableEdgeToEdge(), so content
without explicit inset padding draws (and the close button's touch
target sat) underneath the real system status bar, which intercepted
the taps before the app ever saw them. Fixed with statusBarsPadding()
and by moving the button into its own row above the pager instead of
overlaid on top of it.