feat: cherry-pick PR #183 — multi-provider support, PWA, dynamic models, UI improvements

Cherry-picked from decolua/9router PR #183.
Note: open-sse changes included but need further review due to extensive modifications.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/app/api/providers/[id]/route.js

@@ -30,7 +30,18 @@ export async function PUT(request, { params }) {
   try {
     const { id } = await params;
     const body = await request.json();
-    const { name, priority, globalPriority, defaultModel, isActive, apiKey, testStatus, lastError, lastErrorAt } = body;
+    const {
+      name,
+      priority,
+      globalPriority,
+      defaultModel,
+      isActive,
+      apiKey,
+      testStatus,
+      lastError,
+      lastErrorAt,
+      providerSpecificData
+    } = body;
 
     const existing = await getProviderConnectionById(id);
     if (!existing) {
@@ -47,6 +58,12 @@ export async function PUT(request, { params }) {
     if (testStatus !== undefined) updateData.testStatus = testStatus;
     if (lastError !== undefined) updateData.lastError = lastError;
     if (lastErrorAt !== undefined) updateData.lastErrorAt = lastErrorAt;
+    if (providerSpecificData !== undefined) {
+      updateData.providerSpecificData = {
+        ...(existing.providerSpecificData || {}),
+        ...providerSpecificData,
+      };
+    }
 
     const updated = await updateProviderConnection(id, updateData);