android: the handoff — the pending rounds, the pipeline, and what is unverified

Everything written this session that has not been through the device: rounds 43
to 48 (each patch adversarially verified, 43's transient-notice expectation
fixed), a partial round 49, the pipeline scripts, the Android Auto design and
the icon comparison mock. Also the two harness changes that were never A/B'd —
adaptive waits, which may only shorten a declared wait and never lengthen it,
and a ship that runs the mock walk and the deploy at the same time. The A/B and
its 255-step baseline are in handoff/tools; main stays at what the phone has
actually walked.

handoff/rounds/commit-msg15.txt

@@ -0,0 +1,8 @@
+android: a playlist's cover from a photo on the phone
+
+The storage plugin gains pick_image — the document picker limited to
+images, the picked content copied into the app's cache so the Rust side
+gets a plain path. playlist_cover_set(id, path) is the desktop pick's
+install step split out and shared (squared, the master cover, the row's
+revision moved). A playlist's sheet offers Choose cover photo and Remove
+custom cover; the mock walk exercises both.