Renderer: vendor live-bridge scripts; GPU backend unblocked (60fps)

- emulator/render-bridge/: the pod->Dave's-renderer live bridge (rescued
  from session scratchpad): live_bridge.py (first-person cam from the 0x1f
  pose, arrow-key eye-height trim), fp/chase offline renders, fifobridge,
  diagnostics, gauge_arena[_sound].conf, and launch_pod.ps1 (one-command
  pod+bridge restart: pentapus VPX_EXPLODE + AWE32 sound + GL bridge).
- _backend.py: renderer selection -- vrview_gl.GLRenderer (moderngl) by
  default, VRVIEW_SOFT=1 for the software reference; backend-agnostic
  frame save via last_frame.
- GPU backend runs on side-by-side CPython 3.13 (moderngl/glcontext cp313
  wheels; no MSVC needed): 63fps headless / 60.7 windowed vs 21fps software
  on the same scene, and the GL path also draws the vertex-alpha cloud dome.
- vrview.py: VRVIEW_GAMMA env selects DAC gamma (1.25 live-renderer legacy
  vs 1.7 per the original GAMMA.C) for A/B against the real pod.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

dpl3-revive/patha/vrview.py

@@ -430,6 +430,10 @@ class Renderer:
         self._last_ms = 0.0
         self._psys = {}              # SPECIALFX particle pools by code
         self.light = np.array([0.3, 0.8, 0.5]); self.light /= np.linalg.norm(self.light)
+        # Division 10-bit-DAC output gamma. GAMMA.C (the original source) builds
+        # out = (i/255)^(1/1.7); this live renderer historically used 1.25.
+        # VRVIEW_GAMMA selects it so the two can be compared against the real pod.
+        self.gamma = float(os.environ.get('VRVIEW_GAMMA', '1.25'))
 
     def dcs_matrix(self, board, h):
         m = None
@@ -752,8 +756,9 @@ class Renderer:
                         self.skip / 60.0)
 
         arr = np.clip(img, 0, 255).astype(np.uint8)
-        # Division DAC gamma (out = in^(1/1.25)) -- match render_preview.py
-        arr = (np.power(arr / 255.0, 1 / 1.25) * 255).astype(np.uint8)
+        # Division DAC output gamma (VRVIEW_GAMMA; GAMMA.C = 1.7, live-renderer
+        # legacy = 1.25)
+        arr = (np.power(arr / 255.0, 1.0 / self.gamma) * 255).astype(np.uint8)
         surf = pg.surfarray.make_surface(np.transpose(arr, (1, 0, 2)))
         self.screen.blit(surf, (0, 0))
         pg.display.flip()