chore(android): companion 0.5.1 (vc21) — refresh served APK + deploy handoff

The APK served from the pairing QR predated today's scanner fixes, so
the download-then-scan flow still hit the laggy scanner. Bumps the
version so phones update in place, refreshes the served artifact
(signed v1+v2+v3, verified), and adds the archi-dev-box deploy handoff.

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

Android/app/build.gradle.kts

@@ -11,8 +11,8 @@ android {
         applicationId = "com.archipelago.app"
         minSdk = 26
         targetSdk = 35
-        versionCode = 20
-        versionName = "0.5.0"
+        versionCode = 21
+        versionName = "0.5.1"
 
         vectorDrawables {
             useSupportLibrary = true

docs/HANDOFF-2026-07-23-companion-apk-deploy.md

@@ -0,0 +1,40 @@
+# HANDOFF — deploy companion APK 0.5.1 (vc21) to nodes
+
+**For: the agent on archi-dev-box.** User-reported failure this evening:
+pairing flow on Framework PT — downloaded the companion from the node's
+QR, then the pairing scan didn't work. The APK the node serves predates
+today's scanner fixes; the pipeline below gets the fixed build into the
+user's hands.
+
+## What changed on main today (all merged)
+
+- **Pairing-scanner fix** (`QrScannerOverlay.kt`): ZXing decode attempts are
+  frame-gated (~7/s, was every frame — the CPU contention made the preview
+  stutter badly enough to never decode) and PreviewView uses TextureView (no
+  more black flash on open). This is the likely fix for "doesn't scan".
+- Three-finger menu gesture (was two-finger, collided with scroll) + one-time
+  teaching overlay ~2 min after login.
+- Native wallet QR scanner behind `window.ArchipelagoQr` + WebView file-chooser
+  support; web scan modal hands live scanning to it.
+- npub-keyed saved servers (pairing contract item 1, PR #106).
+- Served APK refreshed: `neode-ui/public/packages/archipelago-companion.apk`
+  is now **0.5.1 / versionCode 21** (this commit).
+
+## What to do
+
+1. Redeploy the web-ui bundle from current main to the active nodes —
+   web root `/opt/archipelago/web-ui/` (NOT a neode-ui/ subfolder), all
+   nodes the user pairs against, at minimum the one Framework PT scans.
+2. Verify the served artifact really updated:
+   `curl -sI http://<node>/packages/archipelago-companion.apk` — size should
+   change (~27 MB build of 2026-07-23), or pull it and check
+   `aapt dump badging` shows `versionCode='21' versionName='0.5.1'`.
+3. The demo stack gets its images from CI (run 100 pushed today with the new
+   web bundle) — confirm the Portainer stack re-pulled, or trigger its
+   redeploy, so the demo QR also serves vc21.
+4. Re-test the user's exact flow: node UI → Companion popup → download APK
+   via QR → install (vc21 updates vc19/vc20 in place) → scan the pairing QR.
+   If the scan still fails on-device with vc21, capture `adb logcat` around
+   the scan and report back — the parser accepts the npub-first QR
+   (`fanchors` self-anchor first), so a remaining failure would be camera-
+   hardware-specific, not format.