8e0c06d888
Add a tree-based category panel that supports expand/collapse of categories. Introduces CatTreeEntry and build_cat_tree to render categories as a collapsible tree. The category panel now displays categories with expand indicators (▶/▼) and shows items under expanded categories. CmdContext gains cat_tree_entry(), cat_at_cursor(), and cat_tree_len() methods to work with the tree. App tracks expanded_cats in a HashSet. Keymap updates: Enter in category panel now triggers filter-to-item. Co-Authored-By: fiddlerwoaroof/git-smart-commit (unsloth/Qwen3.5-35B-A3B-GGUF:Q5_K_M)