Add capture pipeline rate + latency metrics to the Video panel

The FPS readout only measured the host's own render rate, hiding capture stutter.
The Video panel now shows a "Pipeline rates" section:
- Tool render (host FPS / frametime, as before);
- hooked source: Game present (/s, from VideoShare.present_calls deltas), Hook
  publish (/s, generation deltas), and capture->display latency avg/min/max ms;
- WGC source: WGC capture (/s) from a new WindowCapture frame-arrival counter
  (game present + latency are n/a, since WGC frames aren't game-timestamped).

Latency uses a system-wide clock: protocol v11->v12 adds VideoShare.present_qpc,
stamped by the hook at publish (publish_video_frame); the host measures
now_qpc - present_qpc per newly published frame, windowed to min/avg/max each second.

Verified: present_hook_test (x64 + x86) now asserts present_qpc is stamped; full
build x64 + x86 clean; ctest x64 9/9, x86 3/3. The live rate/latency numbers need a
real game mirroring to read meaningfully; wiring validated.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

hook/src/ipc_client.hpp

@@ -217,6 +217,9 @@ public:
 			block_->video.width = width;
 			block_->video.height = height;
 			block_->video.format = format;
+			LARGE_INTEGER qpc{};
+			QueryPerformanceCounter(&qpc);
+			block_->video.present_qpc = qpc.QuadPart; // system-wide clock; host compares directly
 			block_->video.generation.fetch_add(1, std::memory_order_release);
 		}
 	}