v10.4.1

The engine this server spawns had drifted nine releases behind the one a
human gets from npx extension@latest. Agents were building on 4.0.20
while the published CLI was 4.0.29, so every engine fix in that range was
missing from the agent lane, including both theme-colour conversions
shipped this week: a theme.colors project a human built green still
failed when an agent built it. Nothing in this repository changed when
the engine shipped, which is why it went unnoticed until a walk of the
MCP journey read extension_doctor closely.

• extension-create, extension-develop and extension-install move
  from 4.0.20 to 4.0.29, so the agent lane spawns the engine npm serves.
• A nightly engine-pin job now reads npm rather than the working tree
  and fails when a pin trails the published engine, when a pin is a range
  or a dist tag, or when it is missing. It sits beside the existing
  registry-listing watch, because the event that invalidates both happens
  in another repository.