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/mock.js

@@ -17,6 +17,7 @@
     },
     hyperhdrAdjust: {
       host: '', port: 19444, minBrightness: 20, maxBrightness: 100, level: 'rms',
+      restrictToApp: '',
     },
     udp: { host: '', port: 4010, multicastTtl: 4 },
     tcp: { port: 4011, maxClients: 4 },
@@ -156,6 +157,17 @@
           ],
         });
 
+      case 'listApps':
+        return respond(onReply, {
+          returnValue: true,
+          apps: [
+            { id: 'spotify-beehive', title: 'Spotify' },
+            { id: 'netflix', title: 'Netflix' },
+            { id: 'youtube.leanback.v4', title: 'YouTube' },
+            { id: 'com.webos.app.livetv', title: 'Live TV' },
+          ],
+        });
+
       // Same shape as capture_write_diagnostics(): backends at the top level,
       // everything about the machine under "system".
       case 'getDiagnostics':