docs: document the law card schema and its two axes

[ruleofcodedev]

Answers the question behind #11: a consumer rendering law cards from laws --json had to infer that stack: "frontend" means "read satisfiedBy.angular". Nothing said so, so they coded against an observation.

The two axes

field	question	values
stack	selection — does this law run here at all?	frontend, typescript, python, absent (universal)
satisfiedBy keys	guidance — which technology are the instructions written for?	typescript, angular, python

They are orthogonal, and the registry proves it — no key maps onto a single stack:

key	laws	spread
typescript	71	12 typescript + 59 universal
python	70	37 python + 33 universal
angular	67	58 frontend + 3 typescript + 6 universal

angular on TypeScript-stack and universal laws is the clearest evidence that a key is not a stack label. Renaming it to frontend would make the field lie: the advice really is Angular-specific, and a React project matches stack: "frontend".

We already shipped the contract, undocumented

"satisfiedByStacks": {
  "keys": ["typescript", "angular", "python"],
  "stackToKey": { "frontend": "angular", "typescript": "typescript", "python": "python" }
}

The section points renderers at that field rather than a table to copy, so a key added later is picked up rather than missed.

The gap, stated plainly

All 58 frontend laws carry only Angular guidance (#12). A card should say "written for Angular — no React/Vue instructions yet" rather than present Angular steps as universal. The honesty detectionLimits applies to detection, applied to remediation.

Verdict impact

None — documentation only.

Gate

• npm run lint — 0 errors
• node dist/cli.js audit — exit 0