add automatic live stream catch-up

[aedalzotto]

Adds an opt-in option (disabled by default) "Reduce live stream delay (skip to live edge)".
This feature seeks toward the live playback edge as close to real time as the connection allows.
Verified working on real hardware (C2).

Expected behavior:

• When playback falls more than a threshold behind the live edge, it jumps to just behind the edge and shows a toast with how many seconds were skipped.
• Shortly after playback starts, a one-shot skip removes the initial latency.
• The distance it lands behind the edge starts at 2s and adapts to connection quality, so each rebuffering stall widens it up to 8s. Stable playback gradually narrows it down to 1.5s, settling on the smallest delay the connection can sustain. Seek-induced buffering doesn't count as a stall, and the learned margin persists across video changes within a session.
• Seeking back into the DVR suspends the catch-up, showing a "Live catch-up paused" toast. Returning near the edge re-arms it. The player's internal seeks never trigger suspension.