feat(Grid): add customizable background_color property (#50)

- Added sf::Color background_color member with default dark gray
- Python property getter/setter for background_color
- Animation support for individual color components (r/g/b/a)
- Replaces hardcoded clear color in render method
- Test demonstrates color changes and property access

Closes #50

ALPHA_STREAMLINE_WORKLOG.md

@@ -982,4 +982,41 @@ When the window was closed externally via the X button, the cleanup order was in
      - Moved template functions and macros from `UIDrawable_methods.h` into `UIBase.h`
      - Created `UIEntityPyMethods.h` for UIEntity-specific implementations
      - Removed the now-unnecessary `UIDrawable_methods.h`
-   - Result: Better code organization with Python binding code in appropriate headers
+   - Result: Better code organization with Python binding code in appropriate headers
+---
+
+## Phase 6: Rendering Revolution
+
+### Task: Grid Background Colors (#50)
+
+**Status**: Completed
+**Date**: 2025-07-06
+
+**Goal**: Add background_color property to UIGrid for customizable grid backgrounds
+
+**Implementation**:
+1. Added `sf::Color background_color` member to UIGrid class
+2. Initialized with default dark gray (8, 8, 8, 255) in constructors
+3. Replaced hardcoded clear color with `renderTexture.clear(background_color)`
+4. Added Python property getter/setter:
+   - `grid.background_color` returns Color object
+   - Can set with any Color object
+5. Added animation support via property system:
+   - `background_color.r/g/b/a` can be animated individually
+   - Proper clamping to 0-255 range
+
+**Technical Details**:
+- Background renders before grid tiles and entities
+- Animation support through existing property system
+- Type-safe Color object validation
+- No performance impact (just changes clear color)
+
+**Test Results**:
+- Default background color (8, 8, 8) works correctly
+- Setting background_color property changes render
+- Individual color components can be modified
+- Color cycling demonstration successful
+
+**Result**: Grid backgrounds are now customizable, allowing for themed dungeons, environmental effects, and visual polish. This was a perfect warm-up task for Phase 6.
+
+---