fix(display): Vegas resumes after live priority, and six smaller runtime fixes (#644)

- Vegas: a live-priority pause was only lifted from inside run_frame(),
  which returns before that check while paused, so the ticker never came
  back until a restart. run_iteration() now resumes it (the controller
  only calls it when nothing preempts Vegas); start()/stop() clear the
  pause state. Iteration length is timed with the monotonic clock.
- Dim schedule: a per-day disabled day now updates the minute-gate cache,
  so brightness no longer flips back to dim within each minute.
- On-demand: a second request no longer overwrites the rotation resume
  index with the first request's mode.
- Render pipeline: reset() drops the prepared group and deferred queue,
  and a prefetch in flight across a reset discards its result.
- Sync: stop() removes the status file (and the controller's cleanup now
  calls it), standalone removes a stale one at startup, and writes use a
  unique mkstemp temp file.
- render_gate.swap_releases_gil() delegates to frame_timing.
- Stale docstrings/comments corrected.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

src/common/render_gate.py

@@ -48,6 +48,8 @@ import time
 from collections import deque
 from typing import Any, Callable, Deque, List, Optional
 
+from src.common.frame_timing import binding_releases_gil
+
 #: Park background threads this long before the refresh a swap will return on,
 #: so a short C call already under way has finished by then.
 MARGIN_SECONDS = 0.002
@@ -90,19 +92,11 @@ def _unsafe(frame: Any, base: Any) -> bool:
 def swap_releases_gil() -> Optional[bool]:
     """Whether the loaded rgbmatrix binding releases the GIL, or None if none is loaded.
 
-    The rebuilt binding links PyEval_SaveThread and the stock one never does.
-    The same test as src.common.frame_timing.binding_releases_gil (#629); one
-    of the two goes once both have landed.
+    A thin delegate to src.common.frame_timing.binding_releases_gil (#629),
+    which this used to duplicate line for line. The name stays because the
+    coordinator calls it here and tests replace it here.
     """
-    module = sys.modules.get("rgbmatrix.core")
-    path = getattr(module, "__file__", None)
-    if not path:
-        return None
-    try:
-        with open(path, "rb") as handle:
-            return b"PyEval_SaveThread" in handle.read()
-    except OSError:
-        return None
+    return binding_releases_gil()
 
 
 def _held(lock: Any) -> bool: