Round reset + device-creation retry + load-time pump (rejoin trilogy)

1. ROUND RESET (the "picked Hellbringer, got a Blackhawk" field bug):
   trim/prefs finalize the session egg for ONE round, and that was
   permanent for the relay's lifetime -- a rejoin after a mission or
   crash got the stale finalized egg and its new callsign/mech request
   was recorded but never applied.  _maybe_reset_round() (both drop
   paths) restores the original egg/roster/launch state once every pod
   is gone; live beacons re-key by tag position (conn.seat_tag).
   Verified two-round e2e: blkhawk mission -> exit -> RESET -> lok1
   request -> egg rewritten -> the Hellbringer spawned.

2. DEVICE-CREATION RETRY: CreateDevice(HARDWARE_VERTEXPROCESSING) fails
   transiently when a just-exited instance still holds the adapter
   (caught live; also the parked "exit 139" join crash).  The old
   double-failure path called PostQuitMessage(1) -- which does NOT stop
   execution -- and the NULL mDevice deref right after was the real
   crash.  Now: HW->SW retry with 500ms backoff and a 20s deadline,
   then a clean error box + ExitProcess.

3. LOAD-TIME PUMP: mission load is thousands of back-to-back
   synchronous model loads; the starved message pump ghosted the window
   "Not Responding" mid-load.  BTLoadPump() (hooked from
   d3d_OBJECT::LoadObject) pumps + repaints the wait screen at most
   every 150ms pre-run; no-op once the scene is live.

Also: round-reset originals captured after the roster parse (the first
cut crashed the relay constructor -- caught by the two-round test).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

engine/MUNGA_L4/L4D3D.cpp

@@ -75,6 +75,9 @@ struct BTLoadTimer
 
 d3d_OBJECT *d3d_OBJECT::LoadObject(LPDIRECT3DDEVICE9 device, char *fileName)
 {
+	// keep the window alive through long synchronous load stretches
+	extern void BTLoadPump(void);
+	BTLoadPump();
 	BTLoadTimer _lt(fileName);
 	char fullPath[512];
 	sprintf(fullPath, "VIDEO\\%s", fileName);