feat: Add PWA support and consolidate CSS design system

- Add PWA manifest, icons (192x192, 512x512), and service worker
- Register service worker in index.html with Apple mobile web app support
- Consolidate CSS variables and design tokens documentation
- Update PrimeVue overrides for consistent theming
- Refactor data-entry components to use shared CSS patterns
- Add frontend-style-auditor agent for style consistency checks
- Minor OCR validation and job worker improvements
- Update start-prod.sh configuration

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

shared/frontend/styles/login.css

@@ -23,12 +23,13 @@
   border-radius: 16px;
   overflow: hidden;
   border: 1px solid rgba(255, 255, 255, 0.1);
+  background: var(--surface-card);
 }
 
 .login-header {
   text-align: center;
   padding: 2rem 2rem 1rem 2rem;
-  background: white;
+  background: var(--surface-card);
 }
 
 .login-title {
@@ -46,6 +47,7 @@
 
 .login-form {
   padding: 0 2rem 2rem 2rem;
+  background: var(--surface-card);
 }
 
 .login-button {