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-msg35.txt

@@ -0,0 +1,20 @@
+android: a playlist, out of the phone
+
+The desktop has had Export since playlists v2 and the phone had no door onto
+it for one honest reason: `tauri-plugin-dialog` does open Android's
+create-document sheet, but it answers with a `content://` URI and
+`playlist_export` wrote with `std::fs::write`, which cannot take one. The
+storage plugin grew a `create_document` whose Kotlin writes the bytes through
+the ContentResolver — a plugin function called from Rust, not a command, so
+the file never passes through the WebView and nothing was added to the ACL —
+and `playlist_export` now builds the file above the platform fork with the
+same `playlist_formats` writers, so the phone rebuilds no format and the two
+exports cannot drift. The door is the playlist's own sheet, on the page and
+on the shelf card, with the desktop's five profiles in the desktop's order; a
+dismissed sheet says nothing, because nothing happened. The mock walk drives
+it three ways — a file written where the sheet pointed, a sheet dismissed, a
+refusal read back as a sentence — and the phone walk opens the real sheet and
+dismisses it with BACK, writing nothing to the phone. The Kotlin is unbuilt:
+nothing in this tree compiles it, though it is written against
+tauri-android's own `PluginHandle`, `Invoke` and `JSObject` rather than
+against a guess at them.