Web UI: move downloads from bottom bar to ⬇ modal

The fixed bottom #jobs bar ate up to 40vh of screen real estate even
when only one job was running, and on mobile it competed with the URL
input. Replace it with a ⬇ button in the header that:

- shows a badge with active+queued count (turns accent-colored when >0)
- opens a modal listing all jobs when clicked (or with the 'd' shortcut)
- repaints live from the same WS/polling snapshot that drove the old bar

The footer URL input + quality picker stay where they are — that's the
entry point, not the status display.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

PKGBUILD

@@ -19,7 +19,7 @@ optdepends=(
 )
 makedepends=('rust' 'cargo')
 options=('!lto')  # rusqlite bundled sqlite cannot be LTO-linked with rust-lld
-source=("git+https://codeberg.org/anassaeneroi/yt-offline.git")
+source=("git+https://codeberg.org/anassaeneroi/yt-offline.git#branch=main")
 sha256sums=('SKIP')
 
 pkgver() {