docs: record what the Android work established and disproved

Section A of plan 016 is closed and B1 is decided, so the three tenses
move together: CLAUDE.md for what mediacontrols now is, the skill for
what to run, NOTES.md for what was measured and when.

The entry worth reading is the one that disproves a claim written here
earlier in the same session. Dropping x86_64 was expected to make
make android-install fail with INSTALL_FAILED_NO_MATCHING_ABIS.
Measured, it installs and launches: Google's google_apis x86_64 images
carry arm64 translation (abilist = x86_64,arm64-v8a), so the loader
maps lib/arm64/libwails.so and runs it. It dies before any of our code
with SIGILL, and the disassembly names the reason exactly --
`mrs x0, ID_AA64ISAR0_EL1`, Go's internal/cpu reading the arm64 feature
register at runtime init, which the translator does not implement. So
no Go binary starts under it, and that is not a property of this app.

Which closes the last plausible shortcut. There are now three distinct
ways this app fails on an x86_64 Android -- seccomp on the x86_64
build, an unimplemented system register on the translated arm64 one,
and a real device still unverified -- and none of them is a bug in it.
A phone remains the only verification path.

Plan 016 also carries the B2 scope, now decided rather than
recommended: option 1's data model with option 2's surface. The phone
gets home, library browse, now-playing-as-a-view, the queue, search and
playlists; it does not get autotag, downloads, Explore or the 93-control
Settings page, and each of those has a reason written beside it. One
rule for the work: no view forks, because a phone template that copies
a view's is two templates to fix every bug in.

docs/android-release.md

@@ -1,7 +1,7 @@
 # Releasing the Android APK
 
-`.gitea/workflows/android-apk.yml` builds a signed fat APK
-(`arm64-v8a` + `x86_64`) on every `v*` tag and publishes it to Gitea's
+`.gitea/workflows/android-apk.yml` builds a signed `arm64-v8a` APK on
+every `v*` tag and publishes it to Gitea's
 **generic** package registry, which is readable without credentials —
 which is what lets Obtainium poll a plain URL with no token.
 
@@ -98,8 +98,12 @@ publish `1.100.0`**, and never move a tag that has already been built.
 ## What the workflow checks before publishing
 
 - the APK exists and is non-empty;
-- it carries **both** ABIs (`native-code: 'arm64-v8a' 'x86_64'`), or it
-  is not the fat APK it claims to be;
+- it carries **exactly one** ABI (`native-code: 'arm64-v8a'`). x86_64
+  Android cannot run this app at all — `modernc.org/libc` issues a raw
+  `lstat` syscall that Android's seccomp policy forbids, on every
+  x86_64 device and not merely the emulator — so an x86_64 slice would
+  be ~31 MB that runs nowhere, and its reappearance means someone put
+  the ABI back in `app/build.gradle` without knowing that;
 - its `versionCode` is the one derived from the tag;
 - it is **not** signed with the debug key.