v0.2.2: device-sync guards — quit warning, sleep/shutdown inhibition

Quitting mid-transfer now asks (Keep Syncing / Quit Anyway) from
closeEvent, which every quit path hits — including the self-update
restart, which previously bypassed closeEvent via a bare quit() and now
routes through close(). A running sync holds its own GNOME inhibitor
(suspend + logout, "Syncing a playlist to a device") so the machine
won't sleep or shutdown/restart under a copy.

Along the way: the Inhibit D-Bus call marshaled Python ints as signed
against GNOME's (susu) signature, so every call was rejected and the
playback sleep inhibitor had silently never worked — _uint fixes both
holders (verified live: cookies taken, IsInhibited flips, releases
clean).

Also investigated trav's mid-copy Syncthing question: the transfer works
from a click-time snapshot and never reads live library state, so remote
changes can't corrupt it — no state freeze needed. Hardened the one real
gap: a source file relocated under the queue (remote metadata edit
moving files) is now skipped, dropped from the m3u, and reported,
instead of aborting the whole sync.

TASKS.md

@@ -24,6 +24,23 @@ When a round closes, move its finished items to `tasks-done.md`.
 
 # old
 
+## Round 27 — device-sync guards (v0.2.2)
+
+- [x] Quit warning while a transfer is copying (closeEvent; covers X button,
+  Ctrl+Q, MPRIS Quit, and the self-update restart, which used to bypass
+  closeEvent entirely).
+- [x] Machine can't sleep or shutdown/restart mid-transfer: second
+  SleepInhibitor (suspend+logout flags, its own reason text for GNOME's dialog).
+- [x] Found & fixed: the GNOME Inhibit D-Bus call sent signed ints against a
+  (susu) signature, so the *playback* sleep inhibitor had silently never
+  worked — `_uint` marshalling repairs both.
+- [x] Investigated Syncthing changes landing mid-copy: safe by design (the
+  SyncPlan is a click-time snapshot; the worker never reads live library
+  state). Hardened the one gap: a source file relocated under the queue is
+  skipped + dropped from the m3u + reported, instead of aborting the sync.
+
+Tests in `tests/test_round27.py`. Fix round → patch bump **0.2.2**.
+
 ## Round 26 — Device menu: sync playlist to Rabbit R1 (v0.2.0)
 
 - [x] Device menu (left of Track) with "Sync Playlist to Rabbit"; grayed out on