Follow the sibling project's rename to dev-updater

It is no longer "local" -- it serves over WireGuard rather than the LAN --
and it is specifically for developing new apps. Renaming the references
here at the same time keeps one name to search for across both repos.

Also drops the last references to gen-dev-cert.sh, which the in-process
certificate generation replaced: the build script and the Gradle task now
say to start the server once, and test-wg-tunnel.sh reads the
certificates from the XDG directory rather than the repo.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017xn8nHw1tw1R6PtiY1eEtw

app/androidApp/src/main/AndroidManifest.xml

@@ -6,7 +6,7 @@
          network address, including a plain socket to a LAN IP literal.
          Without it the traffic is silently dropped, surfacing only as a
          connect timeout. See MainActivity.kt's runtime request, and
-         local-updater's manifest for the full story. -->
+         dev-updater's manifest for the full story. -->
     <uses-permission android:name="android.permission.ACCESS_LOCAL_NETWORK" />
 
     <application