Make every keyboard shortcut rebindable and drop the iTerm2 preset

[h0x91b]

Summary

Makes every app-level keyboard shortcut rebindable from Settings, and removes the "iTerm2 compatibility" preset in favour of always-on shortcuts you can change one at a time.

The keymap registry now dispatches

src/mainview/keymap.ts used to only document shortcuts — the combos were hand-written a second time as modifier conditions in a 320-line if/else chain in App.tsx, which made rebinding impossible without editing two places. Every branch is now matchesShortcut(e, "<id>"), and display strings are derived from the bindings instead of authored twice.

Bindings match KeyboardEvent.code (layout-independent) with an exact modifier set. A consequence: Mod is now strictly ⌘ on macOS, so the accidental (meta || ctrl) branches are gone and ⌃, / ⌃= / ⌃` reach the terminal where they belong.

Two slots per shortcut

Each shortcut carries a primary combo plus an optional alias, set independently, rather than one flat binding list where "the second way to press it" was an artifact of ordering. Overrides persist per slot — an absent slot keeps its default, null was deliberately emptied — under GlobalSettings.keyboardShortcuts, sparse, so a changed default still reaches everyone who left that row alone.

Settings → Keyboard

A new eighth Settings category. The key chips on each row are the control (no per-row "Change" button — 33 of those is button creep). Taking a combo someone else owns names them first and then empties only the slot that held it. Per-row reset, bulk reset behind confirm(), and a filter that matches the rendered combo as well as the name.

Seven structural shortcuts render read-only with a stated reason rather than being hidden: the g … chord sequences, the ⌘1–9 / ⇧⌘1–9 digit families, the hold-modifier task switcher, Esc, and ⌘R.

The iTerm2 preset is gone

It defaulted to on and existed only to switch four shortcuts off — something the editor now does per row. Deleted: TerminalKeymapPreset, GlobalSettings.terminalKeymap, src/mainview/terminal-keymaps.ts, and all three of its toggles (Settings, the ⓘ popover beside the terminal, and the native Terminal ▸ Keyboard Mode menu).

⌘D, ⌘⇧D, ⌘W and ⌘T are ordinary registry rows in the terminal conflict group, dispatched only while a terminal has focus. Pane navigation (formerly ⌘[ / ⌘]) is dropped rather than rebound: src/bun/tmux/config.ts already binds ⌥+arrows prefix-free, which also removes a latent collision where ⌘[ ran both app-level "back" and pane-focus in the same capture phase.

The ⓘ button now opens the unified ⌘/ overlay on its Terminal tab, which leads with those four combos read from the registry, replacing a partial hover popover.

Also

• keymap-store.ts suspends all dispatch while the recorder is open — both listeners sit on window in the capture phase and the dispatcher registered first, so stopPropagation is too late and a module flag is the only reliable gate.
• Contrast pass on both themes: text carrying meaning moved off --text-muted (the ramp's decorative tier, ~2.99:1 on the light settings surface) to --text-tertiary; the Save button moved to --accent-fill because white on --accent is only 2.98:1 in dark theme.
• Help copy, the UX manifest, and docs/ux/UX_DECISIONS.md updated; decision records 195 and 196.