feat(apple): iPad ⌃⌥⇧Q release chord + click-to-recapture, pixel-grid snap, match-window opt-in

- InputCapture / StreamViewIOS: iPad ⌃⌥⇧Q un-capture chord, recognized from the
  GCKeyboard HID stream (no NSEvent monitor on iOS) for cross-client parity with
  the macOS/Windows/Linux combo; and a click into the video re-engages capture —
  the iPad analogue of macOS mouseDown → engageCapture(fromClick:), with the
  engaging click suppressed toward the host.
- SessionPresenter: snap the aspect-fit sublayer frame to the backing pixel grid.
  AVMakeRect centers the fit rect at fractional points, so the compositor
  resampled the layer — a uniform "everything soft" blur even when the drawable
  was pixel-exact 1:1. Rounding origin + size to device pixels makes the composite
  a true 1:1 blit; idempotent when already aligned.
- MetalVideoPresenter: PUNKTFUNK_BILINEAR_LUMA=1 A/B lever — compiles the shader
  with Catmull-Rom luma off (plain bilinear) to isolate bicubic overshoot from
  upstream fringing.
- SettingsView / StreamView / StreamViewIOS: match-window reverted to opt-in
  (default OFF) — the explicit mode is used and never auto-resized unless enabled.

clients/apple/Punktfunk.xcodeproj/project.pbxproj

@@ -436,6 +436,7 @@
 				INFOPLIST_KEY_CFBundleDisplayName = Punktfunk;
 				INFOPLIST_KEY_GCSupportsControllerUserInteraction = YES;
 				INFOPLIST_KEY_GCSupportsGameMode = YES;
+				INFOPLIST_KEY_ITSAppUsesNonExemptEncryption = NO;
 				INFOPLIST_KEY_LSApplicationCategoryType = "public.app-category.games";
 				INFOPLIST_KEY_NSLocalNetworkUsageDescription = "Punktfunk connects directly to your punktfunk host on the local network to stream video, audio, and input.";
 				INFOPLIST_KEY_NSMicrophoneUsageDescription = "Your microphone is streamed to the connected punktfunk host, where it appears as a virtual microphone.";
@@ -477,6 +478,7 @@
 				INFOPLIST_KEY_CFBundleDisplayName = Punktfunk;
 				INFOPLIST_KEY_GCSupportsControllerUserInteraction = YES;
 				INFOPLIST_KEY_GCSupportsGameMode = YES;
+				INFOPLIST_KEY_ITSAppUsesNonExemptEncryption = NO;
 				INFOPLIST_KEY_LSApplicationCategoryType = "public.app-category.games";
 				INFOPLIST_KEY_NSLocalNetworkUsageDescription = "Punktfunk connects directly to your punktfunk host on the local network to stream video, audio, and input.";
 				INFOPLIST_KEY_NSMicrophoneUsageDescription = "Your microphone is streamed to the connected punktfunk host, where it appears as a virtual microphone.";

clients/apple/Punktfunk.xcodeproj/xcshareddata/xcschemes/Punktfunk-iOS.xcscheme

@@ -49,6 +49,13 @@
             ReferencedContainer = "container:Punktfunk.xcodeproj">
          </BuildableReference>
       </BuildableProductRunnable>
+      <EnvironmentVariables>
+         <EnvironmentVariable
+            key = "PUNKTFUNK_BILINEAR_LUMA"
+            value = "1"
+            isEnabled = "YES">
+         </EnvironmentVariable>
+      </EnvironmentVariables>
    </LaunchAction>
    <ProfileAction
       buildConfiguration = "Release"