feat: renumber lib reference into 4-pillar anatomy

Renumber the 15 reference docs into pillar groups (recipe -> anatomy):
- 01 Build Recipe (entry), 02 Composition Root
- domains: 10 Layering Rules
- contract: 20 Spec-First Routing, 21 CRUD Template, 22 Auth Integration
- interfaces/infra: 30 Infra Adapters
- UI: 40 UI: Auto-Rendered Admin & Custom Pages (new; @aetoskia packages,
  client template, x- catalog via react-openapi MCP module)
- pipelines: 50 Pipeline Scaffold, 51 Worker & Progress, 52 Human-in-the-Loop
- delivery/meta: 90 Drone Pipelines, 91 Versioning & Changelog,
  92 Genericity Matrix, 93 Library Registry, 94 Repository Inventory

MCP module names are unchanged (NN_ prefix stripped); all cross-references
(wiki, templates, hooks, registry) updated; lib index rewritten pillar-first;
build recipe bootstraps the client template. Bundle + HTML sites regenerated.

standards/mcp/templates/app/interfaces/system/__init__.py

@@ -0,0 +1,3 @@
+"""# Summary
+
+System interfaces."""

standards/mcp/templates/app/interfaces/system/routes.py

@@ -0,0 +1,13 @@
+"""# Summary
+
+System route handlers — health probe and other non-resource endpoints.
+"""
+
+
+async def health() -> dict:
+    """Liveness probe — public, unauthenticated.
+
+    Returns:
+        dict: ``{"status": "ok", "service": "app-template"}``.
+    """
+    return {"status": "ok", "service": "app-template"}