toolchain router.
  /freertos/mcp            - MCP, Streamable HTTP (authed)
  /freertos/docs           - tool catalog
  /freertos/files/download - stream a file off the pod (authed)
  /freertos/files/upload   - stream a file onto the pod (authed)
  /freertos/session/reset  - reset the caller's pod; ?purge=true also deletes the saved session (authed)
  /freertos/admin/session/reset - reset or purge a user's session (allowlisted service account)
  /zephyr/mcp            - MCP, Streamable HTTP (authed)
  /zephyr/docs           - tool catalog
  /zephyr/files/download - stream a file off the pod (authed)
  /zephyr/files/upload   - stream a file onto the pod (authed)
  /zephyr/session/reset  - reset the caller's pod; ?purge=true also deletes the saved session (authed)
  /zephyr/admin/session/reset - reset or purge a user's session (allowlisted service account)
  /healthz                    - liveness
  /readyz                     - readiness