fix(plugins): register Android ui_components composables from the generated MobPluginBootstrap

[GenericJam]

Fixes mob_scene3d-q03 (the chopaat repro): the plugin manifest's ui_components declared the Scene3d viewport composable, but nothing consumed it on Android — every host had to hand-register the Compose factory in MainActivity.onCreate, and a host that forgot rendered the component as nothing (MobNativeViewRegistry.render returns silently on an unknown key). iOS already worked via the generated mob_register_plugins() (MobDev.Plugin.IOSBootstrap); this is the Android analog.

Mechanism

New MobDev.Plugin.AndroidBootstrap (pure classify + Kotlin emit) and a ui half spliced into the generated io.mob.plugin.MobPluginBootstrap (NativeBuild.__bootstrap_kotlin__/2), whose registerAll(this) every generated and adopted MainActivity already calls before setContent — so existing hosts get the registrations on their next mix mob.deploy --native with no template or host edit.

• Registry key = ui_components.android.view_module, falling back to ios.view_module (the key is platform-independent — the Elixir module name with dots → underscores; existing manifests only carry it on the iOS side).
• Composable = ui_components.android.composable: used as-is when fully qualified, otherwise qualified with the android.bridge_class package (the composable ships in the plugin's bridge_kt, which declares that package — mob_scene3d: io.mob.scene3d.MobScene3dViewport).
• App package problem dissolved by codegen: MobNativeViewRegistry lives in the app package (MobBridge.kt), which a plugin bridge's own register() can never name — but the generated bootstrap can: __android_app_package__/1 discovers the package of the file defining object MobNativeViewRegistry and every reference is emitted fully qualified.

Silent-nothing becomes impossible

Failure	Where it gets loud
Typo'd / missing composable symbol	Gradle Kotlin compile error (the generated call references it)
Malformed declaration (no registry key, or no composable)	Mix.raise at build, next to the manifest
Non-identifier android.composable	Validator error at validate time (mirrors the swift_struct check)
Declared but unresolvable (bare composable, no bridge — the hand-copied tier-2 workflow)	Generated placeholder registered at registerAll: renders a red "Missing native component: <key> (<plugin>)" tile + Log.e. The host's own registration after registerAll overwrites it, so the documented tier-2 flow keeps working — but forgetting can no longer be silent
Host without the registry (LiveView wrapper / pre-registry template)	Printed build warning; UI codegen skipped (no native-view render path exists there at all)

Verification (compile-level)

Generated a fresh mix mob.new q03host with {:mob_scene3d, path: ...} + config :mob, :plugins, [..., :mob_scene3d] and mob_dev pointed at this branch, then ran the real mix mob.deploy --native --android codegen path. The generated MobPluginBootstrap.kt contains, with no hand edit:

private fun registerUiComponents() {
    // mob_scene3d: Mob_Scene3d_Viewport
    com.example.q03host.MobNativeViewRegistry.register("Mob_Scene3d_Viewport") { props, _send ->
        io.mob.scene3d.MobScene3dViewport(props)
    }
}

…and ./gradlew :app:compileDebugKotlin compiles it green (registration + placeholder variants). Device run not performed (build pool hardware is leased; deploy was pointed at a nonexistent device id on purpose) — the chopaat device evidence for the identical hand-written registration (bead repro) covers the runtime half.

This makes the chopaat MainActivity.kt workaround (tagged mob_scene3d-q03) removable — tracked as chopaat-df3.

Gates

• mix format --check-formatted ✓
• mix credo --strict ✓ (no issues, 311 files)
• mix compile --warnings-as-errors ✓
• mix test ✓ (2180 passed; new: AndroidBootstrap unit suite, __bootstrap_kotlin__/2 splice/order/byte-stability, __android_app_package__ discovery, validator composable accept/reject)
• mix erlfmt --check priv/android/crypto.erl ✓
• mix mob.security_scan --strict: 6 pre-existing HIGH bundled_runtime drift findings in the machine-level ~/.mob/cache OTP tarballs (manifest-vs-binary drift, present on master too, unrelated to this diff); all code layers clean. CI runs the non-strict scan.

No priv/ compile-time resources added (codegen is inline source), so no packed-artifact surface change; the existing packed-artifact regression still passes in mix test.

ADR: decisions/2026-08-30-android-ui-components-bootstrap.md.

🤖 Generated with Claude Code

[GenericJam]

Reviewed: right layer (the deploy-time bootstrap codegen seam where iOS's working analog lives — mob_new correctly untouched), loud-failure design verified at every tier including the proven Gradle failure on a typo'd composable, the manual tier-2 flow preserved via the overwritable placeholder, and the registry-less LiveView-host case handled with a warning instead of broken codegen. Diff sweep clean; CI green (2180 tests + security workflows); chopaat's identical hand-written registration provides the runtime-half evidence. Merging and cutting 0.6.31 — the chopaat workaround removal is tracked (chopaat-df3).