refactor(command): rename commands and extract panel/axis parsers

Rename several commands for consistency:
- save -> save-as (SaveAsCmd)
- save-cmd -> save (SaveCmd)
- enter-search -> search (EnterSearchMode)
- enter-edit -> enter-edit-mode (EnterEditMode)
- exit-search -> exit-search-mode (ExitSearchMode)

Add new commands:
- search-or-category-add
- search-append-char
- search-pop-char
- toggle-panel-and-focus
- toggle-panel-visibility
- command-mode-backspace

Extract parse_panel() and parse_axis() helper functions to replace
repeated match statements. Update documentation comments to reflect
quasi-lisp syntax instead of Forth-style.

Co-Authored-By: fiddlerwoaroof/git-smart-commit (unsloth/Qwen3.5-35B-A3B-GGUF:Q5_K_M)

src/command/mod.rs

@@ -2,7 +2,7 @@
 //! replayed, scripted, and tested without the TUI.
 //!
 //! Commands are trait objects (`dyn Cmd`) that produce effects (`dyn Effect`).
-//! The headless CLI (--cmd / --script) parses Forth-style text into effects
+//! The headless CLI (--cmd / --script) parses quasi-lisp text into effects
 //! and applies them directly.
 
 pub mod cmd;