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).

tools_pc/debug.ps1

@@ -0,0 +1,78 @@
+<#
+  debug.ps1 - launch the PC port under gdb so a playtest crash always leaves
+  a backtrace, even when it is an abort()/sysFatalError (no ge007.crash.log)
+  or a silent exit.
+
+  Usage (from repo root):
+    .\tools_pc\debug.ps1                       # front-end / menu playtest
+    .\tools_pc\debug.ps1 -level_09             # boot straight into a level
+    .\tools_pc\debug.ps1 -Menu 13              # GE_STARTMENU=13 (mission-complete)
+    .\tools_pc\debug.ps1 -Menu 13 -Page 1 -Diff 0
+    .\tools_pc\debug.ps1 -InputLog             # also GE_INPUTLOG=1
+
+  Everything gdb prints goes to gdb.txt. When the game exits (crash or
+  clean) the script prints the FATAL line, the backtrace, and the crash
+  log if one was written.
+#>
+[CmdletBinding()]
+param(
+    [int]$Menu = -1,
+    [int]$Page = 1,
+    [int]$Diff = 0,
+    [switch]$InputLog,
+    [string]$Gdb = "C:\msys64\mingw64\bin\gdb.exe",
+    [Parameter(ValueFromRemainingArguments = $true)]
+    [string[]]$GameArgs
+)
+
+$ErrorActionPreference = "Stop"
+$exe = "build-pc\ge007.x86_64.exe"
+if (-not (Test-Path $exe)) { throw "build the port first: bash build-pc.sh ntsc-final" }
+if (-not (Test-Path $Gdb)) { throw "gdb not found at $Gdb (pass -Gdb <path>)" }
+
+Remove-Item -ErrorAction SilentlyContinue ge007.crash.log, gdb.txt
+
+if ($Menu -ge 0) {
+    $env:GE_STARTMENU      = "$Menu"
+    $env:GE_STARTMENU_PAGE = "$Page"
+    $env:GE_STARTMENU_DIFF = "$Diff"
+    Write-Host "GE_STARTMENU=$Menu page=$Page diff=$Diff" -ForegroundColor Cyan
+} else {
+    Remove-Item -ErrorAction SilentlyContinue Env:\GE_STARTMENU, Env:\GE_STARTMENU_PAGE, Env:\GE_STARTMENU_DIFF
+}
+if ($InputLog) { $env:GE_INPUTLOG = "1" } else { Remove-Item -ErrorAction SilentlyContinue Env:\GE_INPUTLOG }
+
+$gdbArgs = @(
+    "-batch",
+    "-ex", "set pagination off",
+    "-ex", "set confirm off",
+    "-ex", "run",
+    "-ex", "echo `n==== BACKTRACE ====`n",
+    "-ex", "bt full",
+    "-ex", "echo `n==== REGISTERS ====`n",
+    "-ex", "info registers",
+    "-ex", "echo `n==== ALL THREADS ====`n",
+    "-ex", "thread apply all bt",
+    "--args", $exe
+) + $GameArgs
+
+Write-Host "launching under gdb - play until it crashes, output -> gdb.txt" -ForegroundColor Green
+& $Gdb @gdbArgs 2>&1 | Tee-Object -FilePath gdb.txt | Out-Null
+
+Write-Host "`n===================== RESULT =====================" -ForegroundColor Yellow
+$fatal = Select-String -Path gdb.txt -Pattern "FATAL|Unknown GBI|assertion|abort\(\)" | Select-Object -First 5
+if ($fatal) { Write-Host "-- fatal / abort --" -ForegroundColor Red; $fatal | ForEach-Object { $_.Line } }
+
+Write-Host "`n-- backtrace --" -ForegroundColor Red
+$bt = Get-Content gdb.txt
+$i = ($bt | Select-String -Pattern "==== BACKTRACE ====" | Select-Object -First 1).LineNumber
+if ($i) { $bt[$i..([Math]::Min($i + 45, $bt.Count - 1))] | Where-Object { $_ -match '\S' } }
+else    { $bt | Select-String -Pattern "^#\d+|\.c:\d|\.cpp:\d|SIG|exited with code" | Select-Object -Last 40 | ForEach-Object { $_.Line } }
+
+if (Test-Path ge007.crash.log) {
+    Write-Host "`n-- ge007.crash.log --" -ForegroundColor Red
+    Get-Content ge007.crash.log
+} else {
+    Write-Host "`n(no ge007.crash.log - abort()/fatal or clean exit; see backtrace above)" -ForegroundColor DarkGray
+}
+Write-Host "`nfull gdb output: gdb.txt" -ForegroundColor DarkGray