Sync schema id versions to 1.8.2 and stop the drift recurring

[dirkwa]

The schema id URLs still declare 1.5.1 while package.json is at 1.8.2. All 36 references across schemas/ and src/index.js carry the stale version, so 1.7.1, 1.8.0, 1.8.1 and 1.8.2 each published schemas identifying themselves as 1.5.1.

id is the schema's canonical identifier, and schema:publish copies schemas/ into a version-named gh-pages directory — so files served from .../1.8.2/schemas/ declare themselves 1.5.1, and anything resolving or caching by that URL cannot tell four releases apart.

Why it drifted

The schema:version script already existed to do this rewrite, but was referenced by nothing — not prepublish, not any other script — so it only ran when a maintainer remembered. The last run was 3cdea5a, "chore: update schema versions to 1.5.1".

Re-running it alone would just defer the problem to 1.8.3, so this also adds an npm version lifecycle script. The rewrite now runs automatically on every version bump and stages the result.

Note src/index.js registers schemas with tv4 by these same URLs, so it has to move in lockstep with the schema files — another reason to automate rather than rely on a manual step.

Tested

npm test passes (207). Verified the lifecycle hook in a scratch clone: npm version 1.9.0 rewrote all 36 references and staged schemas/ and src/.

Published gh-pages copies for 1.7.x/1.8.x are left as historical artifacts rather than rewritten retroactively — happy to change that if you'd prefer.