feat(backdrop): Capture Window… in-app window pin (TASK 38, Good Dog ONE test)

Click-to-pin an open window as the full-bleed Live backdrop, via the existing
window:<hwnd> capture path (same render layer as game/desktop). Session-scoped:
window:/picker: keys heal to auto on reload (HWND-recycle hazard); pin wins
while the window enumerates, then auto-fallbacks (game → desktop → static); a
dead window's capture session heals to auto, no dead ends.

Fix: ScreenCaptureSourceFactory.Resolve hex-parsed "window:0x<Hwnd>" WITHOUT
stripping the 0x prefix — NumberStyles.HexNumber rejects it, so every pin
resolved null ("No capture target for this key") and the heal silently rolled
back. Same flaw in IsAliveWindowPin (pin-wins guard was dead). Both fixed.

Commit also carries an out-of-scope prerequisite: PillRadioTests.cs:105 had a
committed stray token ("...PrimaryStartButtonLabel soil;", CS1003) blocking the
whole test-project compile — token removed.

Plus the previous session's uncommitted pricing docs (one-time $29/$49) that
share TASKS.md/ai.md/HANDOFF.md.

ytLive.Tests/PillRadioTests.cs

@@ -102,7 +102,7 @@ public sealed class PillRadioTests
             // A session connects: the pill KEEPS its light and the face flips to Start.
             vm.IsConnected = true;
             Assert.True(vm.OnAirPillOn, "the armed signed-out pill must survive the sign-in");
-            Assert.Equal("Start", vm.PrimaryStartButtonLabel soil);
+            Assert.Equal("Start", vm.PrimaryStartButtonLabel);
         }
         finally
         {