tools: wireless-adb beacon — self-healing bridge across drops + port rotation

The phone's wireless-debug port rotates and the bridge drops; this makes
adb reconnect automatically. Three pieces:
- adb-beacon (Android dev app): reads adbd's own mDNS advertisement
  (_adb-tls-connect._tcp) via NsdManager for the live connect port — no
  root, no Shizuku — plus the wlan0 IPv4, and POSTs {ip,port} to fmr every
  time it changes (continuous NSD discovery catches rotation in seconds).
  Foreground service (specialUse) so it survives backgrounding.
- tools/adb-beacon/receiver.py: ~30-line rendezvous on fmr:9099 (secret-
  gated POST stores the latest endpoint; GET returns it). Deployed as
  echolot-adb-beacon.service.
- PC connector polls the endpoint and keeps `adb connect` current.

Dev tooling, separate from the product. Bootstrap: sideload the beacon
APK once (no adb needed); thereafter adb self-heals for everything.

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

echolot-app/adb-beacon/src/main/AndroidManifest.xml

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- SPDX-FileCopyrightText: 2026 Echolot contributors
+     SPDX-License-Identifier: GPL-3.0-or-later -->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_SPECIAL_USE" />
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
+
+    <application
+        android:allowBackup="false"
+        android:label="Echolot ADB Beacon"
+        android:theme="@android:style/Theme.Material.Light">
+
+        <activity android:name=".MainActivity" android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
+        <service
+            android:name=".BeaconService"
+            android:exported="false"
+            android:foregroundServiceType="specialUse">
+            <property
+                android:name="android.app.PROPERTY_SPECIAL_USE_FGS_SUBTYPE"
+                android:value="wireless-debug-endpoint-beacon" />
+        </service>
+    </application>
+</manifest>