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/message-section.css

@@ -207,7 +207,7 @@
 
 .message-scroll-button-wrapper {
   position: absolute;
-  right: 1rem;
+  inset-inline-end: 1rem;
   bottom: 1rem;
   display: flex;
   flex-direction: column;
@@ -274,7 +274,7 @@
 }
 
 .message-quote-button + .message-quote-button {
-  border-left: 1px solid var(--list-item-highlight-border);
+  border-inline-start: 1px solid var(--list-item-highlight-border);
 }
 
 .message-quote-button:hover {