Take the emulator half out of run-android.sh

Which AVD this checkout means, creating it, booting it headless and refusing
to start one the machine has no room for is the same sequence in ai-app,
ai-app-2 and dev-updater. It now lives once, in ~/repos/emulator-tools, and
this script is what is actually specific to this project: a build, an install
and a launch.

Three copies of "boot an emulator" was three places for the memory check none
of them had -- starting one at 2.8 GB available invoked the OOM killer, and
what it took first was another session's emulator.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

AGENTS.md

@@ -225,16 +225,19 @@ first if a remote spawn ever mangles an argument.
   The emulator app reaches it at `https://10.0.2.2:8443`; enroll it with
   `adb -s "$SERIAL" shell "am start -a android.intent.action.VIEW -d 'aiapp://enroll?host=10.0.2.2&port=8443&token=…'"`
   (quote so the device shell doesn't eat the `&`s).
-- **Name the device on every `adb` call.** This checkout runs its own
-  emulator — `run-android.sh` derives the AVD name from the directory, so
-  a second clone gets a second AVD rather than queueing for one shared
-  machine-wide `tdep`. With more than one attached, a bare `adb shell` or
-  `adb get-state` fails with `more than one device/emulator` and a bare
-  `adb shell pm list packages` comes back **empty**, which reads as the app
-  having been uninstalled rather than as the question being ambiguous.
-  Get the serial the way `run-android.sh` does — match `adb -s <serial> emu
-  avd name` against the AVD — or export `ANDROID_SERIAL`, which every
-  `adb` call honours without `-s`.
+- **The emulator is `~/repos/emulator-tools`' business, not this repo's.**
+  `emu up` creates and boots the AVD named after this checkout (`ai-app-2`),
+  refusing when the machine has no room for one; `emu list` says what is
+  attached and what it costs; `emu down` stops it. `run-android.sh` is that
+  plus a build and an install. Run that repo's `install.sh` once if `emu` is
+  missing.
+  The `adb` on `PATH` after sourcing `android-env.sh` is that repo's wrapper,
+  which fills in `-s` from the same rule — so a bare `adb shell` reaches this
+  checkout's emulator and refuses to reach another one's. That defaulting is
+  what makes the old advice unnecessary rather than wrong: with two attached
+  and no `-s`, a bare `adb shell pm list packages` comes back **empty**,
+  which reads as the app having been uninstalled rather than as the question
+  being ambiguous.
 
 ## Where things run (host vs this VM)