ci(windows): enable Developer Mode for pdfrx build

pdfrx requires Windows Developer Mode (its build uses symbolic links);
set AllowDevelopmentWithoutDevLicense on the runner before building so
flutter build windows does not fail the symlink/dev-mode check.

.gitea/workflows/ci.yml

@@ -94,6 +94,22 @@ jobs:
       - name: Flutter version
         run: flutter --version
 
+      # pdfrx REQUIRES Windows Developer Mode (its build creates symbolic links;
+      # without Dev Mode `flutter build windows` fails). Enable it on the runner
+      # by setting the AppModelUnlock registry key (idempotent — a no-op if it is
+      # already on). Requires the runner to be elevated; if it is not, this fails
+      # loudly here, which is correct since the build cannot proceed regardless.
+      - name: Enable Windows Developer Mode (pdfrx symlinks)
+        shell: powershell
+        run: |
+          $ErrorActionPreference = 'Stop'
+          $key = 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\AppModelUnlock'
+          if (-not (Test-Path $key)) { New-Item -Path $key -Force | Out-Null }
+          New-ItemProperty -Path $key -Name 'AllowDevelopmentWithoutDevLicense' `
+            -Value 1 -PropertyType DWORD -Force | Out-Null
+          $v = (Get-ItemProperty -Path $key -Name 'AllowDevelopmentWithoutDevLicense').AllowDevelopmentWithoutDevLicense
+          Write-Host "AllowDevelopmentWithoutDevLicense = $v (1 = Developer Mode on)"
+
       - name: Install dependencies
         run: flutter pub get