Intercepts `Cmd+=`/`Cmd+-`/`Cmd+0` via `before-input-event` before Chromium sees them, so the main
process fully owns zoom. Using `zoom-changed` was unreliable — Chromium applies its own preset step
on top, causing the actual zoom factor to exceed what the window was sized for and clipping content.
The top of the chat window and the left btns were cropped at higher zoom levels. This was
particularly evident with 'Full width' toggled on.

**Changes:**
- Added `applyZoom(zoom)` — resizes and repositions the window proportionally to the zoom factor,
  clamping the left edge to the screen boundary to prevent macOS from clipping panel windows that
  start off-screen

- Updated `showWindow()` to read the current zoom factor and apply it when repositioning, so the
  window doesn't snap back to 1× on summon

- Bumped `BAR_WIDTH` from 1040 → 1100 to give the renderer more horizontal breathing room at default
  zoom

- Added `.zed` to `.gitignore so I could turn off 'format on save' and 'remove trailing whitespace'
  for this project else too many lines were changed