refactor: rename lib/ to core/ for clearer core-module separation

Rename the top-level lib/ directory to core/ so the project root
immediately communicates which code is core platform and which lives
in modules/. PHP namespaces (MintyPHP\*) are unchanged — only the
Composer PSR-4 path mapping moves from lib/ to core/.

Module-internal lib/ directories (modules/*/lib/) are untouched.

Updated across the full stack:
- composer.json PSR-4 mapping
- bootstrap entry points (web/index.php, bin/*, tests/bootstrap.php)
- tooling configs (phpstan.neon, phpunit.xml, php-cs-fixer)
- 26 architecture contract tests
- enforcement-policy, guard-catalog, quality-gates
- all documentation (CLAUDE.md, README, 25 docs/, .agents/skills/)
- bin/qa-extended.sh search paths
- .claude/settings.local.json permission paths

Workflow: .agents/runs/CORE-LIB-RENAME-001/ (Analyst → Planner →
Executor → Code Review (4 findings fixed) → Security Review →
Acceptance Test → Finalizer)

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

docs/tutorial-04-architektur-request-flow.md

@@ -25,15 +25,15 @@ API-Ergänzung:
 ## Schichtregeln
 
 - `pages/**`: Input, Auth/AuthZ, Service-Aufruf, Response.
-- `lib/Service/**`: Business-Regeln und Orchestrierung.
-- `lib/Repository/**`: SQL, Filter, Mapping.
+- `core/Service/**`: Business-Regeln und Orchestrierung.
+- `core/Repository/**`: SQL, Filter, Mapping.
 - `templates/**`: Rendering ohne Business-Logik.
 - Request-Daten in Actions nur über `requestInput()` (keine Input-Superglobals).
 - Validierungsfehler zentral über `FormErrors`; API-Fehler über `ApiResponse::validationFromFormErrors(...)`.
 - Template-AuthZ konsumiert nur vorbereitete `$viewAuth`-Daten (kein `can('...')` im Template).
 - Service-Auflösung in Actions/Helpern über `app(Foo::class)`.
 - Fachliche Audit-Events laufen zentral über `SystemAuditService`.
-- Persistierte Status/Outcome-Werte laufen über die zentrale Taxonomie-Schicht `lib/Domain/Taxonomy/*` (Enums + DB-Checks).
+- Persistierte Status/Outcome-Werte laufen über die zentrale Taxonomie-Schicht `core/Domain/Taxonomy/*` (Enums + DB-Checks).
 - `pages/**/data().php` sind GET-only (`gridRequireGetRequest()`) und normalisieren `limit`/`offset`/`order`/`dir` über Grid-Helper.
 
 ## Einfaches ASCII-Beispiel
@@ -82,5 +82,5 @@ Action
 ## Vertiefung
 
 - Vollständiger Kompass: `/docs/explanation-architektur.md`
-- Regeln für `lib/**`: `/docs/reference-lib-standards.md`
+- Regeln für `core/**`: `/docs/reference-core-standards.md`
 - RBAC-Rechte erweitern: `/docs/howto-rbac-permissions-playbook.md`