fix(memory): use plain JSON Schema for outputSchema instead of Zod objects

[ghost]

Problem

The memory server passes plain objects with Zod values as outputSchema:

outputSchema: {
  entities: z.array(EntitySchema)  // plain object, not z.object()
}

The SDK's McpServer.tool() expects outputSchema to be a full Zod schema (z.object()), not a plain object containing Zod schemas. This causes TypeScript type errors (AnySchema mismatch) and serialization failures when the SDK tries to convert via schemaToJson().

Fix

Wrapped all 9 outputSchema definitions in z.object():

- outputSchema: {
-   entities: z.array(EntitySchema)
- }
+ outputSchema: z.object({
+   entities: z.array(EntitySchema)
+ })

The SDK's schemaToJson() then correctly converts the Zod schema to JSON Schema for the tools/list response.

Fixes #3622