Restrict the brightness sink to one app, picked by name not typed

Confirmed the brightness command applies globally, not per-LED
(serverinfo showed exactly one adjustment object, "id": "default",
covering the whole string), so no LED-count configuration is needed
for this at all -- that question resolved itself once the mechanism
was actually inspected instead of assumed.

For "only react while Spotify is running": only one app can be in the
foreground on webOS at a time, so a "capture the current app" button
in this app's own UI can never work -- pressing it means this app is
foreground, not Spotify. The only workable UI is picking a target from
every *installed* app by name, regardless of what's currently running.

That needed a new native capability this service never had: calling
OUT to another Luna service, not just being called. Two additions:

  foreground_app.c   subscribes once, at startup, to
                      com.webos.applicationManager/getForegroundAppInfo
                      and keeps a thread-safe cache the audio thread can
                      read without a blocking Luna call
  service.c           new listApps method, bridging to
                      com.webos.applicationManager/listApps so the
                      frontend never has to call another service
                      directly -- same rule as everywhere else here

Until the subscription has delivered at least one reply, a restricted
sink treats the target app as inactive, not active -- reacting to
audio when the user explicitly restricted it to one app would be the
wrong failure mode. Verified end to end on the host: engine_smoke.c
opens the sink with a restriction set, confirms it reports itself
correctly inactive against the stub Luna bus (which always "fails" to
call out, exactly like a real host with no bus).

Needed real, linkable stub bodies for LSCall/LSCallOneReply/
LSCallCancel/LSMessageGetPayload/LSErrorInit/LSErrorFree
(test/stubs/luna-service2/lunaservice_stub.c) since foreground_app.c
is the first source file here that's actually linked into a host test
binary rather than only syntax-checked -- service.c/main.c's existing
stub declarations were never called, only compiled against. Confirmed
those really are the correct symbol names by cross-compiling clean
against the real webOS SDK's actual libluna-service2, not just the
stub.

Bumped to 1.0.5.

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

frontend/js/app.js

@@ -28,6 +28,7 @@
     status: null,
     backends: [],
     sinkDefs: [],
+    installedApps: [],
     configPath: '',
     persistent: true,
     bootLinked: false,
@@ -244,6 +245,17 @@
     return out;
   }
 
+  // Fetched once at boot (see the listApps call near the bottom of this
+  // file). Sorted by title there, so this just adds the "no restriction"
+  // default at the front.
+  function installedAppOptions() {
+    var out = [{ value: '', label: 'Always active' }];
+    state.installedApps.forEach(function (a) {
+      out.push({ value: a.id, label: a.title });
+    });
+    return out;
+  }
+
   var CAPTURE_FIELDS = [
     {
       path: 'capture.backend', label: 'Backend', type: 'choice',
@@ -408,6 +420,13 @@
         path: 'hyperhdrAdjust.maxBrightness', label: 'Maximum brightness', type: 'number',
         hint: '0-100. Applied at full level. HyperHDR does not go above 100.',
       },
+      {
+        path: 'hyperhdrAdjust.restrictToApp', label: 'Restrict to app', type: 'choice',
+        options: installedAppOptions,
+        hint: 'Only react to audio while this app is in the foreground. '
+          + 'Picked by name, not typed — only one app can be in front at a '
+          + 'time, so there is no way to "capture the current app" from here.',
+      },
     ],
 
     udp: [
@@ -699,6 +718,9 @@
     if (s.connected !== undefined) {
       bits.push(s.connected ? 'connected' : 'not connected');
     }
+    if (s.restrictToApp) {
+      bits.push(s.restrictedAppActive ? 'active now' : 'waiting for that app');
+    }
     if (s.sendErrors) {
       bits.push(s.sendErrors + ' send errors');
     }
@@ -902,6 +924,16 @@
         renderSinks();
       }, fail);
 
+      // Powers the "restrict to app" picker on the brightness sink. Fetched
+      // once at boot, same as backends/sinks above — the installed-app list
+      // does not change during a session.
+      Luna.listApps(function (reply) {
+        state.installedApps = (reply.apps || []).slice().sort(function (a, b) {
+          return a.title.localeCompare(b.title);
+        });
+        renderSinks();
+      }, fail);
+
       renderCapture();
       renderSystem();
       checkBootLink();