refactor: unify keyboard handling on @opentui/keymap useBindings

[viralcodex]

Summary

• Migrate useKeyboard → declarative useBindings from @opentui/keymap/solid in useKeyboardNav, src/index.tsx (app-level double-escape), and organise.tsx (tool-window left/right paging).
• Establish a single priority hierarchy: useKeyboardNav (100) > organise left/right (50) > app double-esc (10). Input-mode escape uses preventDefault: false so it exits input mode and bubbles to the double-esc handler.
• Drop the duplicate enter binding (terminal keymaps emit return) and remove now-unused useKeyboard / KeyEvent imports.
• Add @opentui/keymap@0.2.0 dependency.

Test plan

• bun test — 111 pass, 0 fail
• bun tsc --noEmit — clean
• Manual: tab / shift+tab / j / k / up / down / return cycle focus in every tool view
• Manual: single ESC in an input exits input mode; second ESC returns to the tools menu (double-esc still works)
• Manual: left / right paging works in the organise tool window and does not fire when the tool window is closed or an input has focus