test(snapshots): make byte/snapshot tests hermetic + re-seed baseline

The COL collision-scanner and the CLAUDE.md cascade resolve ~/.claude from
process.env.HOME (active-config-reader). Snapshot/byte CLIs were spawned with
the developer's real HOME, so they picked up installed plugins/skills and the
user CLAUDE.md — making the v5.0.0 + default-output snapshots machine- and
time-dependent. They were seeded 2026-05-01 with COL=1 (a real ~/.claude skill
collision) and drifted to COL=0 after the polyrepo split: 26 pre-existing
failures unrelated to Batch 1.

Fix (test-only, no production change):
- tests/helpers/hermetic-home.mjs — empty temp HOME, mirroring the pattern
  collision.test.mjs already uses for the COL unit test.
- 7 harnesses spawn CLIs (or call lint()) under the hermetic HOME, so output
  depends only on committed fixtures. Determinism verified across runs.
- Re-seeded all snapshots under hermetic HOME via SEED_SNAPSHOT/UPDATE_SNAPSHOT
  (added a SEED guard to the frozen v5.0.0 byte tests). Snapshots now reflect
  the fixture alone (COL=0, fixture-only activeConfig counts).
- Also re-seeded the unused env-aware snapshots (manifest/whats-active/
  plugin-health), which had baked dozens of real ~/.claude skill/plugin names
  into the committed repo — privacy cleanup.

Full suite: 812/812 green, stable across 3 runs.

tests/scanners/cli-humanizer.test.mjs

@@ -5,7 +5,7 @@ import { fileURLToPath } from 'node:url';
 import { execFile } from 'node:child_process';
 import { promisify } from 'node:util';
 import { readFile, writeFile, unlink, mkdir, access } from 'node:fs/promises';
-import { homedir } from 'node:os';
+import { hermeticEnv, HERMETIC_HOME } from '../helpers/hermetic-home.mjs';
 
 const exec = promisify(execFile);
 const __dirname = dirname(fileURLToPath(import.meta.url));
@@ -13,7 +13,7 @@ const REPO = resolve(__dirname, '../..');
 const FIXTURE = resolve(REPO, 'tests/fixtures/marketplace-medium');
 const BROKEN_PLUGIN = resolve(REPO, 'tests/fixtures/broken-plugin');
 
-const BASELINE_DIR = resolve(homedir(), '.config-audit/baselines');
+const BASELINE_DIR = resolve(HERMETIC_HOME, '.config-audit/baselines');
 const DEFAULT_BASELINE = resolve(BASELINE_DIR, 'default.json');
 
 /**
@@ -25,7 +25,7 @@ async function runCli(cliPath, args, env = {}) {
     const { stdout, stderr } = await exec('node', [cliPath, ...args], {
       timeout: 60000,
       cwd: REPO,
-      env: { ...process.env, ...env },
+      env: hermeticEnv(env),
       maxBuffer: 10 * 1024 * 1024,
     });
     return { stdout: stdout || '', stderr: stderr || '', code: 0 };

tests/scanners/lint-default-output.test.mjs

@@ -3,6 +3,7 @@ import assert from 'node:assert/strict';
 import { resolve, dirname } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { lint } from '../lint-default-output.mjs';
+import { withHermeticHome } from '../helpers/hermetic-home.mjs';
 
 const __dirname = dirname(fileURLToPath(import.meta.url));
 const REPO = resolve(__dirname, '../..');
@@ -10,7 +11,9 @@ const FIXTURE = resolve(REPO, 'tests/fixtures/marketplace-medium');
 
 describe('SC-3 forbidden-words lint (default-output)', () => {
   it('produces no tier1 or tier3 violations across the 6 prose CLIs', async () => {
-    const { failures, warnings } = await lint(FIXTURE);
+    // lint() spawns the prose CLIs inheriting process.env; HOME isolation keeps
+    // the COL collision scanner off the developer's real ~/.claude.
+    const { failures, warnings } = await withHermeticHome(() => lint(FIXTURE));
     const failureSummary = failures
       .map((f) => `[${f.cli}] tier${f.tier} "${f.word}" × ${f.count}`)
       .join('\n  ');

tests/scanners/posture-humanizer.test.mjs

@@ -5,6 +5,7 @@ import { fileURLToPath } from 'node:url';
 import { execFile } from 'node:child_process';
 import { promisify } from 'node:util';
 import { readFile, unlink } from 'node:fs/promises';
+import { hermeticEnv } from '../helpers/hermetic-home.mjs';
 
 const exec = promisify(execFile);
 const __dirname = dirname(fileURLToPath(import.meta.url));
@@ -49,6 +50,7 @@ async function runPosture(flags) {
   const proc = await exec('node', [CLI, FIXTURE, ...flags], {
     timeout: 60000,
     cwd: REPO,
+    env: hermeticEnv(),
   }).catch(err => err); // posture exits non-zero on findings — capture either way
   return {
     stdout: proc.stdout || '',

tests/scanners/scan-orchestrator-humanizer.test.mjs

@@ -5,6 +5,7 @@ import { fileURLToPath } from 'node:url';
 import { execFile } from 'node:child_process';
 import { promisify } from 'node:util';
 import { readFile, unlink } from 'node:fs/promises';
+import { hermeticEnv } from '../helpers/hermetic-home.mjs';
 
 const exec = promisify(execFile);
 const __dirname = dirname(fileURLToPath(import.meta.url));
@@ -44,6 +45,7 @@ async function runOrchestrator(flags) {
     await exec('node', [CLI, FIXTURE, '--output-file', out, ...flags], {
       timeout: 60000,
       cwd: REPO,
+      env: hermeticEnv(),
     });
     const written = await readFile(out, 'utf-8');
     return JSON.parse(written);