M-27: D146 unknown-GBI-opcode -> end DL instead of abort(); tools_pc/debug.ps1

D146 (port/fast3d/gfx_pc.cpp): an unrecognised opcode in the DL walk called
sysFatalError() -> abort() -> whole process dies with no ge007.crash.log
(the crash handler does not cover abort). Seen on the real post-Dam
MISSION COMPLETE screen: "[FATAL] Unknown GBI opcode 0x40c03 at
0x70161a8c" - a front-end 3D model (dossier, D75/D144 family) whose display
list was never built, sitting at a valid DRAM address full of junk. D144
guarded the bad matrix pointer; the walk then hit more garbage. Now: log
loudly (rate-limited x20) and `return` to end the (sub-)DL so the frame
finishes. A real level-render desync is still visible in the log.

tools_pc/debug.ps1: launch the port under gdb from the repo root so a
playtest crash always leaves a backtrace (abort/fatal or silent exit).
-Menu <id> sets GE_STARTMENU; passes through -level_XX etc. Prints the
FATAL line + backtrace + crash log when the game exits.

Verified: GE_STARTMENU=13 mission-complete -> Next chain renders, no abort,
no crash (D75 model cosmetics aside).

port/fast3d/gfx_pc.cpp

@@ -2757,8 +2757,26 @@ static void gfx_run_dl(Gfx* cmd) {
                                      i * 4, r[i], r[i + 1], r[i + 2], r[i + 3]);
                     }
                 }
-                sysFatalError("Unknown GBI opcode 0x%02x at %p.\nw0 %08x\nw1 %08x", opcode, cmd, cmd->words.w0, cmd->words.w1);
-                break;
+                /* D146: an unknown opcode means the DL walk has desynced or
+                 * this DL is garbage (a front-end 3D model whose display list
+                 * was never built - the D75 / D144 family - lives at a valid
+                 * DRAM address full of junk). Aborting the whole process over
+                 * one bad menu model is the wrong trade for a breadth-first
+                 * port: end this (sub-)DL and let the frame finish. Still
+                 * logged loudly, rate-limited, so a real level-render desync
+                 * is not hidden. */
+                {
+                    static int warned = 0;
+                    if (warned < 20) {
+                        warned++;
+                        sysLogPrintf(LOG_ERROR,
+                            "D146: unknown GBI opcode 0x%02x at %p (w0=%llx w1=%llx) - ending DL",
+                            opcode, (void *)cmd,
+                            (unsigned long long)cmd->words.w0,
+                            (unsigned long long)cmd->words.w1);
+                    }
+                }
+                return;
             }
         }
         ++cmd;