Document the local checks and index the example packs (closes #31, closes #34)

[kikashy]

Closes #31. Closes #34.

Two onboarding documents, on separate files, neither touching code.

CONTRIBUTING.md — a Local checks section

The Python version CI currently uses (3.12, stated as what the workflow uses rather than a declared project minimum), the dependency install, and the test command — taken from .github/workflows/conformance.yml rather than restated from memory.

It also carries a warning I earned rather than invented:

Install the dependencies even if the suite appears to run without them. requirements-dev.txt pins jsonschema[format-nongpl], and the format keyword is only checked when those extras are present. Without them, jsonschema silently ignores format, so conformance cases that exist to prove a malformed URI or timestamp is rejected come back valid and the suite passes while checking less than it says it does.

I spent most of a working session treating 2 failed, 45 errors as ambient environment noise before finding the cause. structural-relative-pack-id and structural-invalid-created-at were returning valid. That is precisely the confusion a first-time contributor hits with no way to diagnose it, and it is worth four sentences in the contributor guide.

examples/README.md — an index of the five packs

A compact table linking each example once, naming its synthetic domain and one feature genuinely worth opening that file for. These were derived by reading the documents, not guessed:

Example	Why open it
data-request-intake-triage	the only optional evidence requirement, and the only attestation evidence
minimal-expense-approval	clearest ordered comparisons — in, greater-than, less-than-or-equal — plus a nested not
records-disposition-review	evidence-light by design, so rule structure carries the decision
software-change-review	two independent evidence-present conditions inside one all
supplier-invoice-approval	an exception alongside a not, worth reading together because they are not the same thing

With links to TESTING.md, docs/field-guide.md and the schema, and the standing notice: synthetic and non-operational, not authorization or proof any decision is safe, no real or sensitive data, and no fetching of example source locators during ordinary validation.

Suite: 64 passed, 529 subtests.

🤖 Generated with Claude Code

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