harden: restore gate baseline, split dev/prod PHP profile, atomic module runtime build

Phase A — Gate Reliability:
- Fix typography token violations in app-breadcrumb.css
- Switch QG-006 from composer cs:check to direct php-cs-fixer
- Align all docs/skills with new gate command

Phase B — Production Profile:
- Multi-stage Dockerfile: dev (xdebug) / prod (no xdebug)
- Compose files target explicit build stages

Phase C — Module Runtime Hardening:
- Atomic staging+swap build in ModuleRuntimePageBuilder
- SHA-256 fingerprint from manifest content + page entries
- 11 new regression tests for build safety and fingerprint drift

Task: STARTERKIT-HARDENING-ONPREM-001

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.agents/skills/starterkit-php-style-ci/references/ci-dry-run.md

@@ -7,7 +7,7 @@ CI soll nur pruefen, nicht formatieren.
 ## Minimaler Check
 
 ```bash
-composer cs:check
+vendor/bin/php-cs-fixer fix --config=.php-cs-fixer.dist.php --dry-run --diff --verbose
 ```
 
 ## Erwartung