Migrate web keyboard shortcuts to TanStack hotkeys manager

- replace window keydown listeners with `@tanstack/react-hotkeys` registrations in chat, sidebar, and context menu flows
- add `shortcutToRawHotkey` and `shortcutsForCommands` helpers for normalized, deduplicated hotkey mappings
- add focused keybinding tests and lockfile/package updates for new hotkeys deps
db5681ec87Julius Marminge committed on 2/18/2026, 5:26:22 AMparent9e877f5
7 files changedLine totals unavailable