refactor(simplify): one plan read in red proof, one list marker, one put-back rule [skip-docs]

/simplify over ed6699d..HEAD (closing review of the remediation):
- red-proof reads and parses the step once (planStep) for the test list and
  tests_only; normTest goes, plan-schema exports normPlanPath, also used by
  plan-scope-sweep.
- plan-schema builds LIST_ITEM and the 1.9 File: line from one LIST_MARKER;
  the below-1.9 File: regex ends in a lookahead instead of slicing back one.
- the workflow script hoists tripletOf and puts back through dedupByTriplet.
- coordinator-contract keeps the rank in its JSDoc only; engine-findings
  drops a redundant String().
- tests: reuse knownIssues, trekplan19Block, step1Fields, one red-proof cli
  helper with childEnv, one payload-pair builder; drop a test the decision-20
  definition test covers.

No behaviour change. Suite 2462 (2460/0/2).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lib/verification/plan-scope-sweep.mjs

@@ -38,7 +38,7 @@
 import { readFileSync, existsSync, realpathSync } from 'node:fs';
 import { spawnSync } from 'node:child_process';
 import { resolve, relative, dirname, isAbsolute, sep } from 'node:path';
-import { sliceSteps, parseStepFields, entryPaths, testFirstFiles, extractPlanVersion, usesFilesGrammar } from '../parsers/plan-schema.mjs';
+import { sliceSteps, parseStepFields, entryPaths, testFirstFiles, extractPlanVersion, usesFilesGrammar, normPlanPath as norm } from '../parsers/plan-schema.mjs';
 import { parseManifest } from '../parsers/manifest-yaml.mjs';
 import { isMain } from '../util/is-main.mjs';
 
@@ -60,8 +60,6 @@ function pathsIn(text) {
   return out;
 }
 
-const norm = p => p.replace(/\\/g, '/').replace(/^\.\//, '');
-
 /** Every path the plan names: Files, Test first File, manifest expected_paths. */
 export function plannedPaths(planText) {
   const out = new Set();