v10.9.0

The client ran its browser work through CLI packages pinned three minor
releases back, so an agent driving the MCP got 4.0.30's behavior while the
same person running extension on their own machine got 4.1.2's. Every fix
shipped in between reached the terminal and stopped at the MCP.

• extension-create, extension-develop and extension-install move from
  4.0.30 to 4.1.2. The browser, logging and install paths the MCP tools call
  into now behave the way the documented CLI does.
• No tool surface changes: the same tools take the same inputs and answer the
  same shapes.