fix(schema): document strict Ajv use and test the schema compiles strictly

[ara-stock]

What

The README now shows how to compile schema/tclk1-frames.schema.json under Ajv's default strict mode: collect every x-tclk-* key the schema uses and register it with ajv.addKeyword before compile. A new test compiles the whole schema that way with a default Ajv2020, and also checks that an unregistered default instance still rejects it. ajv@8.20.0 (already the locked version) is added as a root dev dependency for the test.

Why

Fixes #199 with option (b). A default new Ajv2020().compile(schema) throws on x-tclk-canonicalPattern, and nothing compiled the whole document, so integrators found out at runtime. Following @maho0638's note, the keyword list is derived from the schema instead of hard-coding three names, so #177 / #185 (x-tclk-runtimeConstraint) keep working once merged. Thanks to @vanilla3 and @bdunn77 for confirming the reproduction. The schema and SPEC.md are unchanged.

Checks

• pnpm install --frozen-lockfile && pnpm -r --include-workspace-root build
• pnpm -r --include-workspace-root test
• Golden vectors untouched
• CHANGELOG.md has an [Unreleased] entry
• Docs that would now be wrong are updated: README.md
• New surface on the money path: nothing new

I used an AI assistant (Claude) while preparing this. I reproduced the issue and checked the change and tests myself.

[vanilla3]

Thanks for picking this up. Deriving the keyword set from the schema, as @maho0638 suggested, is better than the hard-coded three names in the patch I'd prepared.

One small thing in the README snippet: import Ajv2020 from "ajv/dist/2020.js" followed by new Ajv2020() runs fine in Node. Under TypeScript with module: "Node16", the same setting as this repo's tsconfig.base.json, it fails with TS2351: This expression is not constructable. CI doesn't catch it because tsconfig.json only includes src, and vitest doesn't type-check. The named export type-checks and runs:

import { Ajv2020 } from "ajv/dist/2020.js";

Checked on 5cc4ab9 with ajv 8.20.0 by copying the snippet verbatim into a .ts file. tsc --module node16 --moduleResolution node16 --strict exits 1 with the default import and 0 with the named one, and both forms run under Node. The same change would apply to the import in tests/schema-strict.test.ts, for consistency.

[ara-stock]

Thanks, reproduced: with --module node16 the default import gives TS2351 and the named export type-checks. Switched both the README snippet and tests/schema-strict.test.ts to import { Ajv2020 } from "ajv/dist/2020.js" in 73b582a; the test still passes.