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.

README.md

@@ -54,7 +54,7 @@ text sources, chat on-stream, the social bar, mic/desktop audio with auto-duck a
 recording, variable quality tiers with auto step-down, one-click go-live + scheduling, stream
 resilience (auto-reconnect inside YouTube's grace, one-click back on air), built-in monetization
 awareness (reward capture, session reports, YPP journey tracker), Alerts — all free and ungated;
-the subscription only removes the branding flash.
+the one-time license only removes the branding flash.
 
 ## Structure