test(#1074): add additive per-file workflow size baseline guard (PR 1/3) (#1089)

* test(#1074): add additive per-file workflow size baseline guard (PR 1/3)

Introduces a committed per-file size baseline scheme alongside (not replacing)
the existing tier anti-creep tests. Green by construction — the baseline
records current sizes, so both schemes pass side by side during migration.

- scripts/lib/allowlist-ratchet.cjs: add assertFileBaseline (third pure helper,
  same injected-fail style) — per-file growth/shrink/add/remove diff vs baseline.
- scripts/workflow-size.cjs: single source of truth for LF-normalized byte
  counting (#683) + workflow enumeration, shared by the guard and the generator
  so they can never measure differently. Lives in scripts/ root (NOT scripts/lib/)
  because it is dev/CI-only tooling — scripts/lib/ is bundled into the installed
  runtime, scripts/ root is not, so this keeps it out of the shipped payload.
- scripts/update-size-baseline.cjs + npm run size:baseline: regenerate the
  snapshot (sorted keys, trailing newline, idempotent).
- tests/workflow-size-baseline.json: generated snapshot (88 workflows).
- tests/workflow-size-budget.test.cjs: import the shared counter (drops the
  duplicated local byteCount) and add the per-file baseline describe block.
- Tests for the helper, the shared module, and the generator (incl. round-trip
  and fault-injection cases).

Refs #1074. Part 1 of 3; PR 2 swaps enforcement, PR 3 covers the agent test.

* test(#1074): regenerate workflow baseline after Update-branch merge with next

The 'Update branch' merge (652a916b) pulled in next's update.md change (#1090)
without regenerating the snapshot, leaving the per-file baseline stale by one
file. Re-ran `npm run size:baseline` so the committed baseline matches the
merged workflow files.

Refs #1074.

---------

Co-authored-by: Tom Boucher <trekkie@nomorestars.com>

package.json

@@ -103,6 +103,7 @@
     "lint:docs": "node scripts/lint-docs-required.cjs",
     "lint:legacy-name": "node scripts/lint-legacy-dir-name.cjs",
     "ci:test-scope": "node scripts/ci-test-scope.cjs",
+    "size:baseline": "node scripts/update-size-baseline.cjs",
     "changeset": "node scripts/changeset/new.cjs",
     "changelog:render": "node scripts/changeset/cli.cjs render",
     "test": "node scripts/run-tests.cjs",