Initial release

• Full conditional formatting inventory across all tabs — color swatches, gradient previews, readable summaries, and clickable range chips
• Delete, duplicate, and reorder rules; multi-select for bulk delete, copy, and export
• Copy rules to other tabs with their exact ranges; move rules between spreadsheets via JSON export and import
• Duplicate detection with safe one-click merge — ambiguous groups are flagged for manual review instead of merged
• No-op rule detection (rules whose formatting changes nothing) with one-click cleanup
• JSON backup and restore for a rule, a tab, or the whole workbook, with tab-by-tab import mapping and validation
• Per-tab undo backed by snapshots that survive closing the sidebar, plus Clear undo history
• Honest limits on very large spreadsheets — every cap is announced, nothing is silently truncated
• Keyboard and screen-reader accessible throughout