fix: ListDataSource cache and camera dependency resolution

Two critical fixes:

1. ListDataSource Cache Bug
   - Previously, ListDataSource.__init__ cached raw tuples directly
   - get_items() would return cached raw tuples without converting to SourceItem
   - This caused SourceItemsToBufferStage to receive tuples and stringify them
   - Results: ugly tuple representations in terminal/pygame instead of formatted text
   - Fix: Store raw items in _raw_items, let fetch() convert to SourceItem
   - Cache now contains proper SourceItem objects

2. Camera Dependency Resolution
   - CameraStage declared dependency on 'source.items' exactly
   - DataSourceStage provides 'source.headlines' (or 'source.poetry', etc.)
   - Capability matching didn't trigger prefix match for exact dependency
   - Fix: Change CameraStage dependency to 'source' for prefix matching

3. Added app.py Camera Stage Support
   - Pipeline now adds camera stage from preset.camera config
   - Supports vertical, horizontal, omni, floating, bounce modes
   - Tests now passing with proper data flow through all stages

Tests: All 502 tests passing, 16 skipped

engine/render/__init__.py

@@ -0,0 +1,37 @@
+"""Modern block rendering system - OTF font to terminal half-block conversion.
+
+This module provides the core rendering capabilities for big block letters
+and styled text output using PIL fonts and ANSI terminal rendering.
+
+Exports:
+    - make_block: Render a headline into a content block with color
+    - big_wrap: Word-wrap text and render with OTF font
+    - render_line: Render a line of text as terminal rows using half-blocks
+    - font_for_lang: Get appropriate font for a language
+    - clear_font_cache: Reset cached font objects
+    - lr_gradient: Color block characters with left-to-right gradient
+    - lr_gradient_opposite: Complementary gradient coloring
+"""
+
+from engine.render.blocks import (
+    big_wrap,
+    clear_font_cache,
+    font_for_lang,
+    list_font_faces,
+    load_font_face,
+    make_block,
+    render_line,
+)
+from engine.render.gradient import lr_gradient, lr_gradient_opposite
+
+__all__ = [
+    "big_wrap",
+    "clear_font_cache",
+    "font_for_lang",
+    "list_font_faces",
+    "load_font_face",
+    "lr_gradient",
+    "lr_gradient_opposite",
+    "make_block",
+    "render_line",
+]