chore(windows): clean up build/packaging - drop vendored driver binaries + the LLVM-21 pin

Now that the drivers build from source in CI, remove the dead checked-in binaries and
the toolchain cruft they left behind:

- Delete packaging/windows/{pf-vdisplay,gamepad-drivers}/ (the prebuilt .dll/.inf/.cat/.cer).
  pack-host-installer.ps1 builds + signs all three drivers from the drivers/ workspace and
  nothing reads the vendored dirs anymore; stage-pf-vdisplay.ps1's -VendorDir is now a
  mandatory build-output path, not a vendored default.
- Drop the LLVM-21 pin. The vendored bindgen 0.71->0.72 bump (the shipping pack already
  builds green on the runner-default clang 22) retired the bindgen-0.71 layout-test overflow
  that needed LLVM 21.1.2, so windows-drivers.yml + provision-windows-wdk.ps1 no longer
  install/point at C:\llvm-21 (~898 MB off a fresh provision) - both driver builds now use one
  toolchain (clang 22 + bindgen 0.72).
- pack -SkipBuild on the gamepad build (build-pf-vdisplay.ps1 already builds the whole
  workspace), build-web.ps1 reaps a stale node too, deploy-dev.ps1 nefconc path + comments.
- Reword the vendored-driver references (build scripts, .iss, READMEs, the vite web-bundle
  comment) to the build-from-source reality.

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

scripts/windows/README.md

@@ -50,9 +50,9 @@ and log in with the password the installer shows on its final page. To change it
 powershell -ExecutionPolicy Bypass -File scripts\windows\build-web.ps1
 ```
 
-`bun install && bun run build`, installs the externalized server deps into `.output/server`
-(with the `@unom` `.npmrc`), then restarts the `PunktfunkWeb` task and checks `:3000/login`. Use
-this to iterate on the console against an installed host — `web-setup.ps1` (or a fresh install) is
+`bun install && bun run build` (Nitro `noExternals` -> a self-contained `.output`, no
+`node_modules`/`.npmrc`), then restarts the `PunktfunkWeb` task and checks `:3000/login`. Use
+this to iterate on the console against an installed host - `web-setup.ps1` (or a fresh install) is
 what creates the task in the first place.
 
 ## Typical flow after pulling new code

scripts/windows/build-web.ps1

@@ -23,7 +23,7 @@ if ($LASTEXITCODE -ne 0) { throw "web build failed (exit $LASTEXITCODE)" }
 
 Write-Host "restarting $task ..."
 & schtasks /end /tn $task 2>$null | Out-Null
-Get-CimInstance Win32_Process -Filter "Name='bun.exe'" -ErrorAction SilentlyContinue |
+Get-CimInstance Win32_Process -Filter "Name='bun.exe' OR Name='node.exe'" -ErrorAction SilentlyContinue |
   Where-Object { $_.CommandLine -match 'index\.mjs' } |
   ForEach-Object { Stop-Process -Id $_.ProcessId -Force -ErrorAction SilentlyContinue }
 Start-Sleep 2