Ask Dev Updater for the checkout, not for the app inside it

Dev Updater's unit is a project -- a directory in a checkout -- that
produces components, so this declaration belongs at the repository root
where it can say where each half lives. `cwd` is how a component says
that, and it is what the old file was working around: sitting in `app/`,
it reached the backend with `../server/Cargo.toml` and `../server/service`,
which described the layout backwards.

So the file says what this repository produces: the backend, built and
serviced in `server/`, and then the APK, built in `app/`. The order is
unchanged and still the point -- a failing APK build leaves the phone the
APK it already had rather than half of a matched pair.

The service script gains dev-updater's note about lingering. A user
service stops at logout unless `loginctl enable-linger` is set, which for
this one matters more than for a build server: the phone reaches ai-server
whether or not anyone is logged in at the desk.

**This changes the project path, so the phone's existing entry (at
~/repos/ai-app/app) has to be removed and the checkout root added
instead**, and its components accepted once.

Verified against dev-updater's current parser rather than by reading its
schema: the declaration loads, `cargo build --release` resolves into
server/, app/build-apk.sh into app/, the service script to an absolute
path, and APK discovery from the root still finds the built APK.
`./server/service status` prints not-installed and exits 0.

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

.dev-updater.ron

@@ -0,0 +1,33 @@
+// Read by Dev Updater. Structured as the body of the config: no outer
+// parentheses, so nothing here is indented for the sake of a wrapper.
+//
+// This file sits at the checkout root because the project Dev Updater
+// serves is the whole repository -- one checkout producing two things.
+// Each component says where it lives with `cwd`, relative to this
+// directory, rather than one of them reaching out of the other with `../`.
+
+// What to call this project before there is a build to read a label from.
+// A built APK wins: it is the authority on what will actually install.
+label: "AI Sessions",
+
+// Walked in order, and the order is the point: the backend is built and
+// delivered first, so a failing APK build leaves the phone the APK it
+// already had rather than half of a matched pair.
+components: [
+    Server(
+        name: "backend",
+        build: "cargo build --release",
+        cwd: "server",
+        // Installs into whichever user-service manager is here, and is how
+        // ai-server is started, stopped and asked about. See the script.
+        service: "server/service",
+    ),
+    Apk(
+        name: "app",
+        // Resolved against this directory, and run in `app/` -- the script
+        // cds to its own directory anyway, so the cwd is here to say where
+        // the app is rather than because the build needs it.
+        build: "app/build-apk.sh",
+        cwd: "app",
+    ),
+],