ci(lint): detect broken venv (stale base interpreter) and rebuild

The venv at F:\CI\python\venv may exist but be broken if its pyvenv.cfg points to a deleted base interpreter (e.g. a stale actions/setup-python tool_cache). Detect this by running 'python --version' and rebuild the venv with py.exe -3.11 if it fails.

.gitea/workflows/lint.yml

@@ -81,15 +81,28 @@ jobs:
           $ErrorActionPreference = 'Stop'
 
           # Production venv lives at F:\CI\python\venv (per AGENTS.md).
-          # If missing, bootstrap it via the Windows Python launcher (py -3.11),
+          # If missing or broken (pyvenv.cfg points to a deleted base interpreter,
-          # since the act_runner SYSTEM service does NOT have plain "python" in PATH.
+          # e.g. a stale actions/setup-python tool_cache), rebuild it via the
+          # Windows Python launcher (py -3.11). The act_runner SYSTEM service
+          # does NOT have plain "python" in PATH, but py.exe is installed system-wide.
           $venvPy = Join-Path $env:VENV_DIR 'Scripts\python.exe'
-          if (-not (Test-Path $venvPy)) {
+
-            Write-Host "Venv missing, bootstrapping at $env:VENV_DIR"
+          $venvOk = $false
+          if (Test-Path $venvPy) {
+            & $venvPy --version 2>&1 | Out-Null
+            if ($LASTEXITCODE -eq 0) { $venvOk = $true }
+          }
+
+          if (-not $venvOk) {
+            Write-Host "Venv missing or broken, (re)bootstrapping at $env:VENV_DIR"
+            if (Test-Path $env:VENV_DIR) {
+              Remove-Item $env:VENV_DIR -Recurse -Force
+            }
             $launcher = (Get-Command py.exe -ErrorAction Stop).Source
             & $launcher -3.11 -m venv $env:VENV_DIR
             if ($LASTEXITCODE -ne 0) { throw "venv creation failed" }
           }
+
           Write-Host "Using venv python: $venvPy"
           & $venvPy --version
           if ($LASTEXITCODE -ne 0) { throw "python --version failed" }