process: derived artifacts are accepted on dev once per beta (#697)

The screenshot fingerprint and golden baselines stop being a tax on every
task branch:

- Task branches no longer commit docs/images/** or golden baselines. On a
  branch the screenshot freshness stays a preflight warning; the review
  prompt, REVIEWER.md and AUTHOR.md drop check-docs as a per-task gate.
- beta-derived.yml refreshes them on dev in one bot commit before the beta
  candidate: canonical docs capture + docs:accept --reviewed, golden from
  the golden-images artifact of a completed Validate on dev +
  golden:accept --reviewed. A changed frame or scene is accepted only when
  named in the inputs; undeclared differences refuse. Baseline commits carry
  Release: and Baseline-Reviewed:; the subject is not a candidate subject.
- classify-changes: the Release: trailer on an issue/* branch no longer
  switches on the heavy set. ci:full / ci:golden do: process-track emits
  full=true, the review gate dispatches Validate with full=true and does not
  accept a light proof.

Canon: PROCESS.md §3 п.13, §5.1, §8, §11.4; CONTRIBUTING.md.

Issue: #697
User-Visible: no
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018qZfe7YS4rqEMKoVeS3GKd

test/classify-changes.test.mjs

@@ -236,3 +236,20 @@ test('#510 AC1 / #601 AC1: мутанты по диффу запрашивают
   assert.equal(heavyGatesRequested({ eventName: 'push', headMessage: 'x\n\nRelease: v1.2.3' }), true);
   assert.equal(heavyGatesRequested({ eventName: 'workflow_dispatch', fullInput: 'true' }), true);
 });
+
+test('#697: на ветке задачи трейлер Release: тяжёлый набор не включает, на dev — как прежде', () => {
+  const acceptance = 'test: accept golden\n\nIssue: #687\nUser-Visible: no\nRelease: v1.78.0-beta.9\nBaseline-Reviewed: https://github.com/o/r/actions/runs/1';
+  assert.equal(heavyGatesRequested({ eventName: 'push', headMessage: acceptance, refName: 'issue/687-x' }), false);
+  assert.equal(heavyGatesRequested({ eventName: 'push', headMessage: acceptance, refName: 'refs/heads/issue/687-x' }), false);
+  assert.equal(heavyGatesRequested({ eventName: 'push', headMessage: acceptance, refName: 'dev' }), true, 'кандидат на dev');
+  assert.equal(heavyGatesRequested({ eventName: 'push', headMessage: acceptance }), true, 'без ветки — прежнее правило');
+  assert.equal(heavyGatesRequested({ eventName: 'workflow_dispatch', fullInput: 'true', refName: 'issue/687-x' }), true,
+    'ci:full/ci:golden — dispatch full=true на ветке задачи');
+  assert.equal(screenshotsGateMode({ eventName: 'push', headMessage: acceptance, refName: 'issue/687-x' }), 'warn');
+  const run = (env) => execFileSync(process.execPath, ['scripts/classify-changes.mjs', '--heavy'], {
+    encoding: 'utf8', env: { ...process.env, ...env },
+  }).trim();
+  assert.equal(run({ EVENT_NAME: 'push', HEAD_MESSAGE: acceptance, REF_NAME: 'issue/687-x' }), 'heavy=false\nmutants_requested=false');
+  const workflow = readFileSync(new URL('../.github/workflows/validate.yml', import.meta.url), 'utf8');
+  assert.equal((workflow.match(/REF_NAME: \$\{\{ github\.ref_name \}\}/g) || []).length >= 2, true, 'оба вызова знают ветку');
+});