Settings: clamp logo SVGs to 18px chip + endpoint dropdown gets logo

Provider SVGs in providers.js declare only viewBox (no width/height),
so when injected into the 18×18 logo chips they fell back to the
browser default of 300×150 and blew out the row.

- CSS: SVGs inside settings logo chips (`span[id$="-logo"]`,
  the 18px wrappers in fallback rows) now stretch to 100%/100% of
  their container.
- Added matching `-logo` chip next to the Endpoint dropdowns in
  Default Chat Model and Utility Model cards.
- New `_syncEndpointLogo` helper mirrors the selected endpoint
  option's text label through providerLogo() (the select value is
  a UUID and wouldn't match anything otherwise), and
  `_fillEndpointSelect` calls it on each render.

static/index.html

@@ -1397,6 +1397,7 @@
             <div class="settings-col">
               <div class="settings-row">
                 <label class="settings-label">Endpoint</label>
+                <span class="adm-model-logo" id="set-defaultEpSelect-logo" style="display:inline-flex;align-items:center;justify-content:center;width:18px;height:18px;flex-shrink:0;opacity:0.9;color:var(--fg);"></span>
                 <select id="set-defaultEpSelect" class="settings-select"></select>
               </div>
               <div class="settings-row">
@@ -1420,6 +1421,7 @@
             <div class="settings-col">
               <div class="settings-row">
                 <label class="settings-label">Endpoint</label>
+                <span class="adm-model-logo" id="set-utilityEpSelect-logo" style="display:inline-flex;align-items:center;justify-content:center;width:18px;height:18px;flex-shrink:0;opacity:0.9;color:var(--fg);"></span>
                 <select id="set-utilityEpSelect" class="settings-select"><option value="">—</option></select>
               </div>
               <div class="settings-row">