feat(ui): add dynamic RTL layout support

- Sync document.documentElement.dir dynamically from I18nProvider
  based on selected locale (RTL for 'he', LTR for all others)
- Flip MUI Drawer anchor props (left/right) reactively via isRTL()
- Convert ~60 physical CSS directional properties to logical equivalents
  (border-inline-start/end, inset-inline-start/end, margin-inline-*, etc.)
- Add [dir="rtl"] overrides for translateX animations (sidebar slide,
  resize handle hit-area extensions, settings nav selection nudge)
- Preserve intentional direction:rtl + text-align:left truncation tricks
  (file path display in .truncate-start and .files-tab-selected-path)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/ui/src/styles/messaging/prompt-input.css

@@ -65,8 +65,8 @@
 .prompt-input-overlay {
   position: absolute;
   bottom: 1rem;
-  left: 0.75rem;
-  right: 0.75rem;
+  inset-inline-start: 0.75rem;
+  inset-inline-end: 0.75rem;
   display: flex;
   flex-wrap: wrap;
   gap: 0.5rem;
@@ -85,7 +85,7 @@
 .prompt-nav-buttons {
   position: absolute;
   top: 0.25rem;
-  right: 0.25rem;
+  inset-inline-end: 0.25rem;
   bottom: 0.25rem;
   display: flex;
   flex-direction: column;