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/app/api/providers/validate/route.js

@@ -1,6 +1,6 @@
 import { NextResponse } from "next/server";
 import { getProviderNodeById } from "@/models";
-import { isOpenAICompatibleProvider, isAnthropicCompatibleProvider } from "@/shared/constants/providers";
+import { isOpenAICompatibleProvider, isAnthropicCompatibleProvider, isCustomEmbeddingProvider } from "@/shared/constants/providers";
 import { getDefaultModel } from "open-sse/config/providerModels.js";
 import { resolveOllamaLocalHost } from "open-sse/config/providers.js";
 
@@ -35,6 +35,37 @@ export async function POST(request) {
         });
       }
 
+      // Custom Embedding nodes: probe /models (most embedding APIs are OpenAI-compatible)
+      if (isCustomEmbeddingProvider(provider)) {
+        const node = await getProviderNodeById(provider);
+        if (!node) {
+          return NextResponse.json({ error: "Custom Embedding node not found" }, { status: 404 });
+        }
+        const baseUrl = node.baseUrl?.replace(/\/$/, "");
+        const modelsRes = await fetch(`${baseUrl}/models`, {
+          headers: { "Authorization": `Bearer ${apiKey}` },
+        });
+        if (modelsRes.ok) {
+          return NextResponse.json({ valid: true });
+        }
+        // Auth errors are definitive
+        if (modelsRes.status === 401 || modelsRes.status === 403) {
+          return NextResponse.json({ valid: false, error: "Invalid API key" });
+        }
+        // Fallback: probe /embeddings with a common test model — many providers lack /models
+        const embedRes = await fetch(`${baseUrl}/embeddings`, {
+          method: "POST",
+          headers: { "Authorization": `Bearer ${apiKey}`, "Content-Type": "application/json" },
+          body: JSON.stringify({ model: "test", input: "ping" }),
+        });
+        // 401/403 = bad key; anything else (including 400 "model not found") means key works
+        isValid = embedRes.status !== 401 && embedRes.status !== 403;
+        return NextResponse.json({
+          valid: isValid,
+          error: isValid ? null : "Invalid API key",
+        });
+      }
+
       if (isAnthropicCompatibleProvider(provider)) {
         const node = await getProviderNodeById(provider);
         if (!node) {