Enhance image and embedding provider support

- Added new image models for GPT 5.2, 5.3, and 5.4, including capabilities for text-to-image and editing.
- Updated embedding handling to include optional dimensions in requests.
- Introduced support for custom embedding providers, allowing dynamic fetching and validation of custom nodes.
- Improved image generation handling with Codex integration, including progress tracking and error handling.
- Enhanced UI components to support adding custom embeddings and displaying their status.

src/sse/services/auth.js

@@ -15,11 +15,12 @@ let selectionMutex = Promise.resolve();
  * @param {Set<string>|string|null} excludeConnectionIds - Connection ID(s) to exclude (for retry with next account)
  * @param {string|null} model - Model name for per-model rate limit filtering
  */
-export async function getProviderCredentials(provider, excludeConnectionIds = null, model = null) {
+export async function getProviderCredentials(provider, excludeConnectionIds = null, model = null, options = {}) {
   // Normalize to Set for consistent handling
   const excludeSet = excludeConnectionIds instanceof Set
     ? excludeConnectionIds
     : (excludeConnectionIds ? new Set([excludeConnectionIds]) : new Set());
+  const preferredConnectionId = options?.preferredConnectionId || null;
   // Acquire mutex to prevent race conditions
   const currentMutex = selectionMutex;
   let resolveMutex;
@@ -87,7 +88,16 @@ export async function getProviderCredentials(provider, excludeConnectionIds = nu
     const strategy = providerOverride.fallbackStrategy || settings.fallbackStrategy || "fill-first";
 
     let connection;
-    if (strategy === "round-robin") {
+    // Pin to preferred connection if specified and available
+    if (preferredConnectionId) {
+      connection = availableConnections.find((c) => c.id === preferredConnectionId);
+      if (connection) {
+        log.info("AUTH", `${provider} | pinned to ${connection.id?.slice(0, 8)} (${connection.name || connection.email || "unnamed"})`);
+      }
+    }
+    if (connection) {
+      // skip strategy
+    } else if (strategy === "round-robin") {
       const stickyLimit = providerOverride.stickyRoundRobinLimit || settings.stickyRoundRobinLimit || 3;
 
       // Sort by lastUsed (most recent first) to find current candidate