feat(keymap): allow direct bindings for leader commands

[Maxteabag]

Commands available only in the leader menu cannot currently be assigned a direct key. Allow main leader commands in action_keys within app scopes, so query_normal.edit_query_in_editor: "ctrl+g" opens the editor while the existing leader shortcut remains available.

The bindings retain command guards, explicit state restrictions, and existing conflict detection. Direct editor shortcuts are dispatched before the text widget consumes them, with autocomplete precedence resolved by the existing key router. Aliases and independent unbinding are supported. Vim submenu motions and dialog scopes remain outside this command-promotion feature.

Closes #321.

Validation:

• 205 keyboard, editor, clipboard, paste, and undo tests passed, including 41 new regression cases.
• Headless keypress tests cover Ctrl+G, Ctrl+A, Ctrl+C, Ctrl+V, leader shortcuts, and autocomplete precedence.
• Wheel build succeeded.
• Changed code passes Ruff; the existing C901 and RUF100 diagnostics in keymap_manager.py also reproduce on main.