Build the code-style / formatting check module (`ln` / clean-code)

[StarshipSuperjam]

The engine opened this item itself — you didn't create it.

What this is. The engine does not yet check your code's style or formatting — that capability is a planned module that hasn't been built.

• What it is: an owed engine module (the design calls it ln / clean-code) that would check code style and formatting, the way the other installed modules check structure and coherence.
• Why it's here: an audit of the engine's own deferred build work found this is genuinely unbuilt. Because it isn't built, the engine honestly tells you so — once in the project README it seeds, and once in the first-run setup copy. Those honest notes are correct and stay until the module ships.

What happens next. Nothing right now — this is tracked so the gap stays visible.

• A future Build session builds the module as its own reviewed-and-merged change.
• When it ships, the two "style isn't checked" notes (in .engine/provisioning/readme-seed.md and the first-run copy in .engine/tools/instantiator.py) are removed in the same change.
• If you want it sooner, you can ask for it to be prioritised.

More detail.

• Where the engine says style isn't checked yet