Story 5.2: Video Widget Width Customization

Implements configurable video widget widths for small and large dock layouts:
- Add widgetWidthSm and widgetWidthMd world settings (defaults: 83px, 150px)
- Add width dropdown selectors in Director's Board UI
- Apply width settings to participant avatars via CSS custom properties
- Update strip width/height calculations to use custom widths
- Add localization strings for widget width settings
- Add CSS styling for widget width dropdown controls
- Fix Handlebars template syntax for select element selected values

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

templates/roster-strip.hbs

@@ -41,7 +41,7 @@
   </div>
 
   {{!-- Participant list --}}
-  <ul class="sp-strip__participants" role="list">
+  <ul class="sp-strip__participants" role="list" style="--sp-widget-width: {{widgetWidth}}px;">
     {{#if isEmpty}}
       {{!-- EmptyStatePanel --}}
       <li class="sp-strip__empty-state" role="listitem">
@@ -58,7 +58,7 @@
                   role="button"
                   aria-label="{{name}} — {{stateLabel}}"
                   data-tooltip="{{name}} — {{stateLabel}}"
-                  aria-pressed="false">
+                  aria-pressed="false" style="width: {{../widgetWidth}}px; min-width: {{../widgetWidth}}px;">
 
             {{!-- Video container for stream-access mode (full AV replacement) --}}
             {{#if hasStreamAccess}}