Memory drawer: edit type, wider panel, scrollable content

The Memory drawer's edit form now includes a Type selector so you can reclassify a Memory as Context, Decision, Fact, or Asset without leaving the drawer. The drawer itself is wider on desktop (680 px) to give long Memories room to breathe, and the Memory content is now height-constrained with its own scroll so the metadata and actions below it stay visible without needing to scroll the whole panel. The update_memory MCP tool also accepts a new optional type parameter so AI clients can reclassify memories in the same edit call.