Fix button highlighting bugs and optimize memory for Raspberry Pi CM5

[No0ne558]

Description

This PR addresses button highlighting issues and introduces memory efficiency optimizations targeted for the Raspberry Pi CM5.

Changes

• fix: Remove broken static tile cache causing button highlighting bugs
  The static cache optimization in Layer::Rectangle() was fundamentally broken - static variables persisted across all rendering calls, causing stale cache values to be used when different buttons needed different textures.

  • Remove static current_tile, current_origin_x, current_origin_y cache
  • Each Rectangle() call now properly sets XSetTile and XSetTSOrigin
  • Ensures correct texture rendering for all button states

• fix: Preload all textures to fix button highlighting bug
  The lazy texture loading optimization conflicted with the static tile cache in Layer::Rectangle(), causing buttons to incorrectly show highlighted state.

  • Add PreloadAllTextures() function to load all textures at startup
  • Call PreloadAllTextures() after ResetView() during initialization
  • Ensures consistent Pixmap values before any rendering occurs

• perf: Add memory efficiency optimizations for Raspberry Pi CM5
  Object Pool System:

  • Add object_pool.hh with thread-safe ObjectPool template
  • Add PooledObject RAII wrapper for automatic return to pool
  • Add BufferPool for fixed-size char buffer pooling
  • Configurable max pool size (default 64 objects)

  Thread Pool & Async I/O:

  • Add thread_pool.hh with ThreadPool for async operations
  • Add WriteBehindBuffer for deferred writes
  • Add CloseAsync() for non-blocking printer operations
  • Add 5-second socket timeouts to prevent hangs

  Memory Management Improvements:

  • Convert Report* to std::unique_ptr in 8 zone files
  • Add O(1) Count() caching for DList/SList (was O(n))
  • Add lazy texture loading with LRU cache in term_view
  • Reduce CharQueue default size from 2MB to 256KB
  • Add RemoveAndDelete() helpers for linked lists
  • Add RAII for KeyValueInputFile/KeyValueOutputFile

  Quick Fixes:

  • Cache term->GetSettings() pointer in hot paths
  • Fix socket leaks in socket.cc and loader_main.cc

  Target: Raspberry Pi CM5 with 2GB RAM optimization
  Tests: 83/83 passing

Testing

All tests pass (83/83). Manual testing on Raspberry Pi CM5 recommended for memory optimizations.