Add remappable controller controls with a Controller Options tab

Add a player_controls config group that maps game actions to controller
inputs, and a Controller Options menu tab to rebind them in-headset.

- 45 actions: movement, click/double-click, jump, fire, and the engine's own
  keyboard hotkeys (posture, save/load, weapon/MFD select, etc.), sent to the
  engine as synthetic key events. Cheat and dead hotkeys are not exposed.
- Press-to-capture rebinding with per-input exclusivity, Reset to Defaults
  (built-in defaults, then questshock.config.default.json), and new defaults:
  left stick moves/strafes, right stick turns.
- Controller profiles for Touch, Vive and generic OpenXR
  (res/controller_profiles/), matched to the active interaction profile at
  runtime, with a fatal dialog if a profile's bindings are rejected at
  startup.
- The menu's thumbstick locomotion is disabled while the Controller Options
  tab is open or a capture is active. A scrollable list with a tap-to-jump
  scroll bar handles the long action list.
- Opening the menu pauses a running game and resumes it on close.
- Reset Position now keeps the player's facing instead of turning the screen
  to the current gaze.
- Play the intro video in the game's language (engine patch 23), falling back
  to English.
- Watchdog and shared-key handling for stuck movement keys, plus key-edge
  logging.

res/controller_profiles/generic.json

@@ -0,0 +1,9 @@
+{
+  "name": "Generic OpenXR Controller",
+  "interaction_profile": "/interaction_profiles/khr/simple_controller",
+  "image": "generic.png",
+  "controls": [
+    {"id": "left_trigger", "label": "Select (Left)", "anchor_x": 0.30, "anchor_y": 0.60},
+    {"id": "right_trigger", "label": "Select (Right)", "anchor_x": 0.30, "anchor_y": 0.60}
+  ]
+}