feat: editor font-size match, hot model default, Shift-H/L nav

- .cm-editor pinned to font-size 1rem so the input matches the
  output pane (CodeMirror 6 defaults smaller)
- refreshLoaded(isInitial=true) on first load picks the hot model
  as the dropdown default — avoids the 5-15s disk reload on the
  first translation. Subsequent refreshes don't override the user's
  manual selection.
- document-level Shift-H / Shift-L cycle focus across controls
  (source → target → model → editor → button), suppressed when
  focus is inside CodeMirror so vim's viewport H/L still work.

CHANGELOG.md

@@ -9,6 +9,11 @@ Versioning: [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Added
 - Vim bindings in the input via CodeMirror 6 + `@replit/codemirror-vim` (loaded from esm.sh, no build step). Supports `i`/`Esc`, `hjkl`, word/line motions, `dd`/`yy`/`p`, undo/redo, `/` search, `:` command line. Auto-disabled on touch devices (detected via `(pointer: coarse)`) where modal editing fights the virtual keyboard.
+- `Shift-H` / `Shift-L` cycle focus across the page controls (source → target → model → editor → button) like `Shift-Tab` / `Tab`. Suppressed inside the editor where vim already owns those motions.
+- On page load, the model dropdown defaults to whichever model Ollama already has hot — skips the 5-15 s disk-reload pain on the first translation. After load it follows the user's manual selection.
+
+### Changed
+- Editor font-size pinned to `1rem` to match the output pane (CodeMirror 6 ships smaller by default).
 
 ## [0.1.0] - 2026-06-09