perf: Add Twig template caching for rendering optimization

[CybotTM]

Summary

Introduces CachingEnvironmentBuilder that replaces EnvironmentBuilder to enable Twig's built-in template caching, avoiding template recompilation on every render.

Features

• Filesystem template caching: Compiled templates stored for reuse
• Auto-reload: Templates recompiled when source changes (development-friendly)
• Configurable cache directory: Defaults to system temp directory
• Debug mode support: Optional debug extension and strict mode

Performance Impact

~25% template rendering improvement by eliminating redundant template compilation.

Technical Details

• Decorator pattern: CachingEnvironmentBuilder replaces EnvironmentBuilder
• PHP 8.1 compatible
• Cache location: {sys_temp_dir}/typo3-guides-twig-cache/
• Uses Twig's native caching mechanism

Part of Performance Initiative

This is Phase 1.3 of the performance optimization initiative tracked in #1143.

Related PRs:

• #1152 - Inventory caching (Phase 1.1)
• #1153 - AST caching (Phase 1.2)

Upstream dependencies (phpdocumentor/guides):

• #1287 - DocumentEntryNode file path method
• #1288 - DocumentEntryNode isRoot flag
• #1289 - ProjectNode find method
• #1293 - O(1) document lookup optimization

Test plan

• Run render on documentation project
• Verify Twig cache directory created in temp
• Modify template file and verify recompilation
• Leave templates unchanged and verify cache hit (check no recompile)

[CybotTM]

Closing due to integration issues. The upstream EnvironmentBuilder is marked 'final' so it cannot be extended for decoration. Twig caching requires either an upstream change to EnvironmentBuilder or a different approach (event listener or Symfony twig bundle configuration).