feat(playback): mouse-drag seek with true seeking via rodio 0.22

Add click/drag scrubbing on the progress bar: dragging moves a preview
knob (pure render, no audio work) and a single seek commits on release.
The bar's geometry is recorded each frame so the mouse handler can map a
column to a position, and mouse capture is enabled/disabled with the
terminal (and on the panic hook).

Replace the seek mechanism entirely. The old skip_duration path decoded
and discarded every sample from zero on the calling thread, which froze
the UI when seeking deep into long tracks. Upgrade rodio 0.17 -> 0.22 and
use Player::try_seek, a symphonia-backed true seek (~5ms, even while
paused). The decoder is built seekable with the file's byte length so VBR
MP3s seek accurately. This also fixes the keyboard arrow-key seek, which
shared the same skip_duration path.

Migration touches the renamed rodio API: Sink -> Player, OutputStream ->
MixerDeviceSink/DeviceSinkBuilder, current_frame_len -> current_span_len,
NonZero channel/sample-rate types, and native f32 samples (no
convert_samples). Covered by an ignored audio-device test asserting the
seek succeeds and returns promptly.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: program247365