Fix /storage endpoint to default to HTML

Same content negotiation fix as other endpoints - default to HTML
for browsers, only return JSON if explicitly requested.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

server.py

@@ -3046,11 +3046,15 @@ import storage_providers
 
 @app.get("/storage")
 async def list_storage(request: Request, user: User = Depends(get_optional_user)):
-    """List user's storage providers. HTML for browsers, JSON for API."""
+    """List user's storage providers. HTML for browsers (default), JSON only if explicitly requested."""
+    # Check if JSON explicitly requested
+    accept = request.headers.get("accept", "")
+    wants_json = "application/json" in accept and "text/html" not in accept
+
     if not user:
-        if wants_html(request):
-            return RedirectResponse(url="/login", status_code=302)
-        raise HTTPException(401, "Authentication required")
+        if wants_json:
+            raise HTTPException(401, "Authentication required")
+        return RedirectResponse(url="/login", status_code=302)
 
     storages = await db.get_user_storage(user.username)
 
@@ -3071,10 +3075,11 @@ async def list_storage(request: Request, user: User = Depends(get_optional_user)
                     masked[k] = v
             storage["config_display"] = masked
 
-    if wants_html(request):
-        return await ui_storage_page(user.username, storages, request)
+    if wants_json:
+        return {"storages": storages}
 
-    return {"storages": storages}
+    # Default to HTML for browsers
+    return await ui_storage_page(user.username, storages, request)
 
 
 @app.post("/storage")