Post-grab async background swap, upgrade_locked flag to prevent the
upgrade loop from re-inflating a locally-transcoded file, and a
transcode-library CLI backfill for the existing catalog. Bitrate model
calibrated against Silicon Valley's real HEVC bitrate, scaled by
resolution and AV1's encoding efficiency. HDR/2160p and anime excluded
from this first pass. Jellyfin session polling throttles batch
encoding back to 1 stream during active playback.
Library tab gets a cycling filter (all/series/movies/missing/unmonitored)
and sort (title/missing/kind), color-coded kind tags and missing-count
severity, and monitor-toggle without opening detail. Keybinding hints move
out of cramped block titles into a context-aware status bar plus a `?`
help overlay, both driven by one shared keybinding table so they can't
drift apart. Episode status icons and review-queue confidence get the same
severity coloring. Stuck tab gains real selection/focus and can jump
straight to a show's Library detail (needed adding media_item_id to
StalledGrab's query — the one small backend touch in this pass). Adds a
manual refresh-now key.
