Add a navigation history so pages can be walked back and forward.
- nav.rs: a back/forward stack of NavEntry (home, album, artist,
settings); record() on fresh navigation, go_back/go_forward to walk it
- NavButtons: a [<] [>] pair styled like the Discover tab group; inline
beside the Discover tabs and in place of the per-page Back button on
album, artist and settings views
- All navigation routes through Rust (open-album/-artist record entries;
the gear and header menu use NavState.request-settings) so the history
stays accurate; back/forward re-apply entries, re-loading entity pages
- AppShell listens for the mouse back/forward buttons
- can-back / can-forward drive the buttons' enabled state
Also in this round:
- Album header description: render a pre-truncated short string so it
wraps to a couple of lines instead of overflowing the header; the full
text stays in the Read-more modal
- Header queue button uses an ordered-list icon (the previous one read
as a playlist)
cc
vicrodh
12ed5a7c4a