perf: improve commander selection speed and fix color identity display

RELEASE_NOTES_TEMPLATE.md

@@ -1,36 +1,33 @@
 # MTG Python Deckbuilder ${VERSION}
 
+## [Unreleased]
+
 ### Summary
-Major infrastructure upgrade: migrated to Parquet data format with comprehensive performance improvements, combo tag support, simplified data management, and instant setup via GitHub downloads.
+Performance improvements and bug fixes for commander selection and display.
 
-### What's New
-- **Instant Setup** - Download pre-tagged card database from GitHub instead of 15-20 minute initial build
-- **Parquet Migration** - Unified `all_cards.parquet` replaces multiple CSV files for faster, more efficient card storage
-- **Combo Tags** - 226 cards now tagged with combo-enabling abilities for better synergy detection
-- **Parallel Tagging** - Optional 4.2x speedup for card tagging (22s → 5.2s)
-- **Automatic Deduplication** - No more duplicate card printings cluttering your deck options
-- **Built-in Commander Filtering** - Instant identification of 2,751 commanders and 31 backgrounds
+### Added
+_None_
 
-### Improvements
-- **First-Run Experience** - Auto-downloads pre-tagged data on first run (seconds vs. 15-20 minutes)
-- **Faster Startup** - Binary columnar format loads significantly faster than text parsing
-- **Smaller File Sizes** - Single Parquet file is more compact than multiple CSVs
-- **Better Data Quality** - Automatic validation, deduplication, and type checking
-- **Cleaner Organization** - Single source of truth for all 29,857 cards
-- **Web Performance** - Card browser, commander catalog, and owned cards all benefit from faster data access
-- **Weekly Updates** - Pre-tagged data refreshed weekly via GitHub Actions
+### Changed
+_None_
+
+### Removed
+_None_
+
+### Fixed
+- **Color Identity Display**: Fixed commander color identity showing incorrectly as "Colorless (C)" for non-partner commanders in the summary panel
+
+### Performance
+- **Commander Selection Speed**: Dramatically improved response time from 4+ seconds to under 1 second
+  - Implemented intelligent caching for card data to eliminate redundant file loading
+  - Both commander data and full card database now cached with automatic refresh when data updates
 
 ### For Users
-Everything works the same or better! Main visible differences:
-- **First-time users**: Setup completes in seconds (auto-downloads pre-tagged data)
-- Faster load times and data operations
-- Better card recommendations with combo tag support
-- More reliable data handling
-- Web UI includes manual "Download from GitHub" button for instant refresh
+- Commander selection is now **much faster** - expect sub-second response times
+- Color identity labels in deck summaries now display correctly for all commanders
 
-### Technical Details
-- Data stored in `card_files/processed/all_cards.parquet`
-- Boolean flags (`isCommander`, `isBackground`) replace separate CSV files
-- CLI execution: `python -m code.main`
-- Headless execution: `python -m code.headless_runner --config <path>`
-- GitHub Actions and Docker builds updated for Parquet workflow
+### Deprecated
+_None_
+
+### Security
+_None_