docs: refresh README/docs/examples + install scripts for waves 1-4

User-facing documentation drifted behind several waves of feature work
(plugin manifest, hooks, sync command, --weekly, audit skills, Karpathy
skill, CLAUDE.local.md tier, layered hook config). Refresh + fix one
real install bug. Surgical edits only — no rewrites.

README.md:
  - "What's New" block now reflects the plugin manifest, --weekly,
    InstructionsLoaded hook, AGENTS.md interop, CLAUDE.local.md tier,
    layered hook config, and the fail-closed guardian.
  - "What's Included" expanded from 5 numbered bullets to a structured
    list grouping the 5 skills (incl. three forked audit skills),
    2 slash commands, 1 agent, and 3 hook scripts.
  - Components Deep Dive: /sync-claude-md and the guardian's fail-closed
    contract now documented.
  - Project Status: 1.0.0 -> 2.1.0; Quick Stats updated to reflect
    actual component counts.
  - Acknowledgments: attribution to MIT-licensed forrestchang and
    shanraisshan source repos for adapted patterns.

docs/ARCHITECTURE.md, docs/QUICK_START.md, docs/TROUBLESHOOTING.md,
docs/INSTALLATION.md, examples/modular-setup.md, examples/integration-
examples.md:
  - Every "20-300 lines" / ">300 lines" / "exceeds 300 lines" reference
    rewritten to the actual 150-line hard cap.
  - Every ls/Remove-Item path that pointed at the legacy
    ~/.claude/commands/enhance-claude-md/ bundle now points at the
    top-level enhance-claude-md.md + sync-claude-md.md files.
  - integration-examples.md line-bounds shell guard now uses 20..150.

docs/CLAUDE.md:
  - Install-verify ls list extended with the three new audit-skill
    directories so docs match what install.sh actually creates.

install.sh + install.ps1 (REAL FIX, not just docs):
  - The three forked audit skills (claude-md-drift-audit, link-check,
    dependency-rescan) were registered in plugin.json but never copied
    by the direct-install path. Both installers now iterate over them
    after the karpathy-guidelines block, mirroring the same backup +
    nested-duplicate-cleanup pattern. Banner section and uninstall
    instructions list all 5 skills.

Verified:
  - All 5 CLAUDE.md files in this repo still <= 150 lines after edits.
  - install.sh passes bash -n syntax check.
  - Plugin manifest still resolves all 8 referenced paths on disk.
  - README invariants present: 2.1.0, --weekly, hooks/hooks.json,
    both source-repo attributions, three audit skill names.
  - Stale-claim sweep: zero "20-300" / ">300" / "exceeds 300" refs
    remain in docs/ or examples/.

docs/ARCHITECTURE.md

@@ -211,9 +211,10 @@ def calculate_quality_score(self) → int:
 **Validation Categories:**
 
 1. **Length Validation**
-   - Recommended: 20-300 lines
-   - Warning: 300-400 lines (suggest modular)
-   - Error: < 20 or > 400 lines
+   - Recommended: 20–120 lines (sweet spot)
+   - Warning: 120–150 lines (approaching cap)
+   - **Hard cap: 150 lines** — enforced deterministically by `hooks/validate-claude-md.py` on `PostToolUse(Edit|Write)` *and* `InstructionsLoaded`. Files over the cap must be split into chained sub-CLAUDE.md files.
+   - Exempt: any file whose basename ends in `.local.md` (personal-tier override).
 
 2. **Structure Validation**
    - Required sections: Core Principles, Tech Stack, Workflow
@@ -432,9 +433,9 @@ Triggers update if:
 
 ### File Size Limits
 
-- Single file: Max 400 lines (prefer 300)
-- Modular files: Each 150-300 lines
-- Total project: Unlimited with modular
+- Every CLAUDE.md: hard cap 150 lines (no exceptions outside `*.local.md`).
+- Modular split via `@path/to/sub/CLAUDE.md` chain imports when content would exceed the cap.
+- Total project: unlimited via modular chaining + `.claude/rules/*.md` for path-scoped guidance.
 
 ### Caching Strategy