feat: reveal all hidden shapes with Shift+H, release SAM3 VRAM on idle and on demand (REQ-191, REQ-192)

.env.example

@@ -39,6 +39,13 @@ API_PORT=9010
 # dev server from another device.
 CORS_ORIGINS=http://localhost:5173,http://localhost:9000,http://localhost:9010,http://localhost:8080,http://localhost:8000
 
+# ---- GPU --------------------------------------------------------------------
+
+# Seconds SAM3 may sit unused before the app drops it and gives the VRAM back
+# (REQ-192). Default 1200 (20 min) when unset; 0 keeps it resident forever.
+# The next SAM3 call reloads it from cache in ~12 seconds either way.
+# SAM3_IDLE_UNLOAD_S=1200
+
 # ---- recorder (algoritma-batch/batch_video_cropper.py) -----------------------
 # Only needed if you run the 24/7 truck-session recorder. It reads the RTSP
 # stream to detect sessions, then downloads each session from the recording