feat(config-audit): v3.1.0 — /config-audit whats-active inventory command

New read-only command that shows everything Claude Code actually loads for a
given repo — plugins, skills, MCP servers, hooks, CLAUDE.md cascade — with
source attribution (user/project/plugin) and rough token estimates. Helps
identify candidates for disabling without guessing.

Added:
- scanners/lib/active-config-reader.mjs — pure async helper: readActiveConfig,
  detectGitRoot, walkClaudeMdCascade, readClaudeJsonProjectSlice (longest-prefix
  matching for .claude.json projects), enumeratePlugins, enumerateSkills,
  readActiveHooks, readActiveMcpServers, estimateTokens (markdown 4 c/tok,
  json 3.5 c/tok, frontmatter cap 150 tokens, item flat 15)
- scanners/whats-active.mjs — thin CLI shim: --json, --output-file, --verbose,
  --suggest-disables
- commands/whats-active.md — renders tables via Read tool; honors UX rules
- tests/lib/active-config-reader.test.mjs — 36 tests, all green (integration
  fixture built in tmpdir with fake HOME, .claude.json prefix matching,
  plugin discovery, hook/MCP merge from all scopes)

Verified:
- Performance budget: <2s wall-clock (smoke test: 102ms on real repo)
- Token estimates within ±20% of hand-computed values
- Read-only: no writeFile/mkdir/unlink in production code
- Self-audit: Plugin Health scanner reports 0 findings (Grade A)
- Full test suite: 522 tests, 512 pass (10 pre-existing conflict-detector
  failures on main — unrelated to this change, reproducible on clean HEAD)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -7,7 +7,7 @@ Open-source Claude Code plugin marketplace. Solo project by Kjell Tore Guttormse
 ```
 plugins/
   ai-psychosis/          v1.0.0  — Interaction awareness (sycophancy, reinforcement loops)
-  config-audit/          v3.0.1  — Configuration intelligence (health, opportunities, auto-fix)
+  config-audit/          v3.1.0  — Configuration intelligence (health, opportunities, auto-fix, whats-active)
   linkedin-thought-leadership/  v1.2.0  — LinkedIn content pipeline + analytics
   llm-security/          v6.0.0  — Security scanning, auditing, threat modeling
   ms-ai-architect/       v1.8.0  — Microsoft AI architecture (Cosmo Skyberg persona)