Customizable keyboard shortcuts via settings page

[setkyar]

Problem / motivation

All keyboard shortcuts in pi-web are currently hardcoded and cannot be changed by users. Different users have different muscle memory — vim-style j/k, emacs-style C-n/C-p, arrow keys, etc. Power users also want to remap shortcuts like ⌘B (toggle sidebar) or ⌘⇧N (scratchpad) to their own preferences.

Proposed solution

Add a "Keyboard Shortcuts" section to the Settings page (/settings) where users can:

1. See all current shortcut bindings in a readable table/list grouped by category (General, Navigation, Chat Composer, Entry Toggles).
2. Click a shortcut to enter "rebind" mode — press the desired key combination, and it re-maps.
3. A "Reset to defaults" button per category and globally.
4. Shortcuts are persisted as server-backed settings (like other settings), so they survive restarts and work across browsers.
5. Conflict detection: warn the user if they try to map two actions to the same key combination.

Scope / affected code:

• Frontend: web/src/shared/keyboard-nav.js — make all keybindings configurable via a central registry instead of inline addEventListener with hardcoded keys.
• Frontend: web/src/settings/settings.js + settings.html — new section for shortcut rebinding.
• Frontend: web/src/session/live/shortcuts-modal.js — reflect custom bindings in the shortcuts help modal.
• Backend: internal/server/settings.go — add new setting keys to settingDefaults.

PR requirements:

• E2E test (Playwright) covering shortcut rebinding and persistence.
• Screenshots of the settings page with the new shortcut section, and the shortcuts modal reflecting custom bindings.

Alternatives considered

No response

Acknowledgement

• I understand the maintainer triages requests and will invite a PR only if this moves forward.