docs: close doc drift vectors — bidirectional parity, manifest, schema-driven config (#2479)

Option A — ghost-entry guard (INVENTORY ⊆ actual):
  tests/inventory-source-parity.test.cjs parses every declared row in
  INVENTORY.md and asserts the source file exists. Catches deletions and
  renames that leave ghost entries behind.

Option B — auto-generated structural manifest:
  scripts/gen-inventory-manifest.cjs walks all six family dirs and emits
  docs/INVENTORY-MANIFEST.json. tests/inventory-manifest-sync.test.cjs
  fails CI when a new surface ships without a manifest update, surfacing
  exactly which entries are missing.

Option C — schema-driven config validation + docs parity:
  get-shit-done/bin/lib/config-schema.cjs extracted from config.cjs as
  the single source of truth for VALID_CONFIG_KEYS and dynamic patterns.
  config.cjs now imports from it. tests/config-schema-docs-parity.test.cjs
  asserts every exact-match key appears in docs/CONFIGURATION.md, surfacing
  14 previously undocumented keys (planning.sub_repos, workflow.ai_integration_phase,
  git.base_branch, learnings.max_inject, and 10 others) — all now documented
  in their appropriate sections.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/gen-inventory-manifest.cjs

@@ -0,0 +1,109 @@
+#!/usr/bin/env node
+'use strict';
+
+/**
+ * Generates docs/INVENTORY-MANIFEST.json — a structural skeleton of every
+ * shipped surface derived entirely from the filesystem. Commit this file;
+ * CI re-runs the script and diffs. A non-empty diff means a surface shipped
+ * without an INVENTORY.md row.
+ *
+ * Usage:
+ *   node scripts/gen-inventory-manifest.cjs              # print to stdout
+ *   node scripts/gen-inventory-manifest.cjs --write      # write docs/INVENTORY-MANIFEST.json
+ *   node scripts/gen-inventory-manifest.cjs --check      # exit 1 if committed manifest is stale
+ */
+
+const fs = require('node:fs');
+const path = require('node:path');
+
+const ROOT = path.resolve(__dirname, '..');
+const MANIFEST_PATH = path.join(ROOT, 'docs', 'INVENTORY-MANIFEST.json');
+
+const FAMILIES = [
+  {
+    name: 'agents',
+    dir: path.join(ROOT, 'agents'),
+    filter: (f) => /^gsd-.*\.md$/.test(f),
+    toName: (f) => f.replace(/\.md$/, ''),
+  },
+  {
+    name: 'commands',
+    dir: path.join(ROOT, 'commands', 'gsd'),
+    filter: (f) => f.endsWith('.md'),
+    toName: (f) => '/gsd-' + f.replace(/\.md$/, ''),
+  },
+  {
+    name: 'workflows',
+    dir: path.join(ROOT, 'get-shit-done', 'workflows'),
+    filter: (f) => f.endsWith('.md'),
+    toName: (f) => f,
+  },
+  {
+    name: 'references',
+    dir: path.join(ROOT, 'get-shit-done', 'references'),
+    filter: (f) => f.endsWith('.md'),
+    toName: (f) => f,
+  },
+  {
+    name: 'cli_modules',
+    dir: path.join(ROOT, 'get-shit-done', 'bin', 'lib'),
+    filter: (f) => f.endsWith('.cjs'),
+    toName: (f) => f,
+  },
+  {
+    name: 'hooks',
+    dir: path.join(ROOT, 'hooks'),
+    filter: (f) => /\.(js|sh)$/.test(f),
+    toName: (f) => f,
+  },
+];
+
+function buildManifest() {
+  const manifest = { generated: new Date().toISOString().slice(0, 10), families: {} };
+  for (const { name, dir, filter, toName } of FAMILIES) {
+    manifest.families[name] = fs
+      .readdirSync(dir)
+      .filter((f) => fs.statSync(path.join(dir, f)).isFile() && filter(f))
+      .map(toName)
+      .sort();
+  }
+  return manifest;
+}
+
+const [, , flag] = process.argv;
+
+if (flag === '--check') {
+  const committed = JSON.parse(fs.readFileSync(MANIFEST_PATH, 'utf8'));
+  const live = buildManifest();
+  // Strip the generated date for comparison
+  delete committed.generated;
+  delete live.generated;
+  const committedStr = JSON.stringify(committed, null, 2);
+  const liveStr = JSON.stringify(live, null, 2);
+  if (committedStr !== liveStr) {
+    process.stderr.write(
+      'docs/INVENTORY-MANIFEST.json is stale. Run:\n' +
+      '  node scripts/gen-inventory-manifest.cjs --write\n' +
+      'then add a matching row in docs/INVENTORY.md for each new entry.\n\n',
+    );
+    // Show diff-friendly output
+    for (const family of Object.keys(live.families)) {
+      const liveSet = new Set(live.families[family]);
+      const committedSet = new Set((committed.families || {})[family] || []);
+      for (const name of liveSet) {
+        if (!committedSet.has(name)) process.stderr.write('  + ' + family + '/' + name + '\n');
+      }
+      for (const name of committedSet) {
+        if (!liveSet.has(name)) process.stderr.write('  - ' + family + '/' + name + '\n');
+      }
+    }
+    process.exit(1);
+  }
+  process.stdout.write('docs/INVENTORY-MANIFEST.json is up to date.\n');
+} else if (flag === '--write') {
+  const manifest = buildManifest();
+  fs.writeFileSync(MANIFEST_PATH, JSON.stringify(manifest, null, 2) + '\n');
+  process.stdout.write('Wrote ' + MANIFEST_PATH + '\n');
+} else {
+  process.stdout.write(JSON.stringify(buildManifest(), null, 2) + '\n');
+}