Fix Windows blueprint import cleanup

[bcotrim]

Summary

This fixes Windows failures when running blueprints.phar against an existing Studio site using native PHP.

There are two related issues:

1. WXR imports append PHP code to scripts/import-content.php, but that script already starts PHP and does not close it. Adding another <?php/?> wrapper can make the generated import subprocess script invalid.
2. Temporary workspace cleanup can fail on Windows after blueprint execution, likely because files/directories are still briefly held by subprocesses. That cleanup failure should not mask an otherwise successful blueprint run.

Changes

• Remove the extra PHP opening/closing tags around the appended run_content_import([...]) call.
• Catch FilesystemException during final temporary workspace cleanup so a cleanup failure does not fail successful blueprint execution.

Testing Instructions

Tested on Windows using PHP 8.4 and a Studio-created SQLite site.

1. Create a site in Studio.

2. Quit Studio.

3. Ensure the SQLite integration is available at:

   C:\Users\<user>\Studio\<site>\wp-content\plugins\sqlite-database-integration

   If Studio only has it under mu-plugins, create a junction/symlink from plugins to mu-plugins.

4. If the Studio site's wp-config.php does not define DB_NAME, temporarily add:

   define( 'DB_NAME', 'wordpress' );

5. Download and extract a blueprint bundle that imports WXR content, for example:

   http://blueprintlibrary.wordpress.com/?blueprint=829
   

6. As a control, run the latest GitHub blueprints.phar against the site:

   $env:OUTPUT_FILE = "$env:TEMP\blueprints-control-output.jsonl"
   
   php "C:\Users\<user>\Downloads\blueprints.phar" exec "C:\Users\<user>\Downloads\organization-koinonia\blueprint.json" `
     --mode=apply-to-existing-site `
     --site-path="C:\Users\<user>\Studio\<site>" `
     --site-url=http://localhost:<port> `
     --db-engine=sqlite
   
   Get-Content $env:OUTPUT_FILE
   Remove-Item Env:\OUTPUT_FILE

   Before this patch, the run failed with:

   {"type":"error","message":"Failed to remove directory: C:/Users/.../AppData/Local/Temp/wp-blueprints-runtime-..."}

7. Build the patched PHAR:

   composer build-blueprints-phar

8. Run the same blueprint with the patched PHAR:

   $env:OUTPUT_FILE = "$env:TEMP\blueprints-pr280-output.jsonl"
   
   php dist\blueprints.phar exec "C:\Users\<user>\Downloads\organization-koinonia\blueprint.json" `
     --mode=apply-to-existing-site `
     --site-path="C:\Users\<user>\Studio\<site>" `
     --site-url=http://localhost:<port> `
     --db-engine=sqlite
   
   Get-Content $env:OUTPUT_FILE
   Remove-Item Env:\OUTPUT_FILE

9. Confirm the output contains:

   {"type":"completion","message":"Blueprint successfully executed."}

10. Restore wp-config.php if DB_NAME was added only for this test.