Add custom agent creator, Zread MCP, fix model change context continuity

Features added:
- Custom Agent Creator dialog with AI generation support (up to 30k chars)
- Plus button next to agent selector to create new agents
- Zread MCP Server from Z.AI in marketplace (remote HTTP config)
- Extended MCP config types to support remote/http/sse servers

Bug fixes:
- Filter SDK Z.AI/GLM providers to ensure our custom routing with full message history
- This fixes the issue where changing models mid-chat lost conversationcontext

packages/ui/src/stores/session-api.ts

@@ -746,7 +746,12 @@ async function fetchProviders(instanceId: string): Promise<void> {
       })),
     }))
 
-    const filteredBaseProviders = providerList.filter((provider) => provider.id !== "zai")
+    // Filter out Z.AI providers from SDK to use our custom routing with full message history
+    const filteredBaseProviders = providerList.filter((provider) =>
+      !provider.id.toLowerCase().includes("zai") &&
+      !provider.id.toLowerCase().includes("z.ai") &&
+      !provider.id.toLowerCase().includes("glm")
+    )
 
     const extraProviders = await fetchExtraProviders()
     const baseProviders = removeDuplicateProviders(filteredBaseProviders, extraProviders)