feat(settings): editor font size for chat input and code editor (#1325) (#2065)

* feat(settings): add editor font size setting for chat input and code editor

Adds an 'Editor font size' control in Settings > Appearance that sets an
absolute px font size for the chat input textarea and the in-app
CodeMirror editor. Mirrors the existing terminalFontSize lifecycle.

- New store field editorFontSize (default 13, clamp 9-32, step 1) in
  useUIStore with narrow selectors at each consumer.
- Persistence wired through appearanceAutoSave, desktop + runtime API
  types, and persistence.ts read/normalize.
- Settings UI row (NumberInput) with reset to 13, VisibleSetting union
  entry, OpenChamberPage registration, and search index entry
  appearance.editor-font-size.
- Applied as a post-zoom absolute override on the chat input textarea
  and on the CodeMirror theme's content rule, leaving gutter/line-number
  chrome at its existing hardcoded sizes (matches terminal scope).
- All 10 locales translated (en, es, fr, ja, ko, pl, pt-BR, uk, zh-CN,
  zh-TW); no English placeholders in non-English dictionaries.

Refs #1325

* fix(codemirror): use unitless lineHeight so it scales with editor font size

The & rule in the CodeMirror theme set lineHeight to 1.5rem (~24px),
which does not scale when editorFontSize is increased (e.g., 28-32px).
This causes overlapping lines at larger font sizes.

Change to unitless 1.5, which scales proportionally with whatever fontSize
resolves to (dynamic prop or --text-code fallback). Matches browser best
practice for proportional leading.

Review comment: https://github.com/openchamber/openchamber/pull/2065

---------

Co-authored-by: bashrusakh <bashrusakh@users.noreply.github.com>
Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

packages/ui/src/lib/persistence.ts

@@ -594,6 +594,9 @@ const applyDesktopUiPreferences = (settings: DesktopSettings) => {
   if (typeof settings.terminalFontSize === 'number' && Number.isFinite(settings.terminalFontSize) && settings.terminalFontSize !== store.terminalFontSize) {
     store.setTerminalFontSize(settings.terminalFontSize);
   }
+  if (typeof settings.editorFontSize === 'number' && Number.isFinite(settings.editorFontSize) && settings.editorFontSize !== store.editorFontSize) {
+    store.setEditorFontSize(settings.editorFontSize);
+  }
   if (isUiFontOption(settings.uiFont) && settings.uiFont !== store.uiFont) {
     store.setUiFont(settings.uiFont);
   }
@@ -1111,6 +1114,9 @@ const sanitizeWebSettings = (payload: unknown): DesktopSettings | null => {
   if (typeof candidate.terminalFontSize === 'number' && Number.isFinite(candidate.terminalFontSize)) {
     result.terminalFontSize = candidate.terminalFontSize;
   }
+  if (typeof candidate.editorFontSize === 'number' && Number.isFinite(candidate.editorFontSize)) {
+    result.editorFontSize = candidate.editorFontSize;
+  }
   if (isUiFontOption(candidate.uiFont)) {
     result.uiFont = candidate.uiFont;
   }