feat: Add shared components, refactor stores, improve data-entry workflow

Shared Components:
- Add CompanySelector.vue and PeriodSelector.vue components
- Add AppHeader.vue and SlideMenu.vue layout components
- Add shared stores factories (companies.js, accountingPeriod.js)
- Add shared routes factories (companies.py, calendar.py)
- Add shared models (company.py, calendar.py)
- Add shared layout styles (header.css, navigation.css)

Data Entry App:
- Update CLAUDE.md with prod/test server documentation
- Improve nomenclature sync service with better error handling
- Update receipts router and CRUD operations
- Add company/period stores using shared factories
- Update App.vue layout with shared components
- Fix OCRUploadZone file handling

Reports App:
- Refactor stores to use shared factories
- Update App.vue to use shared layout components

Infrastructure:
- Replace start-data-entry.sh with separate dev/test scripts
- Add .claude/rules for authentication, backend patterns, etc.
- Add implementation plan for OCR receipt improvements
- Clean up old documentation files

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

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

.claude/rules/company-period.md

@@ -0,0 +1,19 @@
+# Company & Period Selection Rules
+
+## Store Factories (MANDATORY)
+- Companies: Use `createCompaniesStore()` from `shared/frontend/stores/companies.js`
+- Periods: Use `createAccountingPeriodStore()` from `shared/frontend/stores/accountingPeriod.js`
+- Never implement custom company/period stores
+
+## Components
+- Use `CompanySelector.vue` from `shared/frontend/components/`
+- Use `PeriodSelector.vue` from `shared/frontend/components/`
+- Use `AppHeader.vue` layout from `shared/frontend/components/layout/`
+
+## Backend Endpoints
+- Use `create_companies_router()` factory from `shared/routes/companies.py`
+- Use `create_calendar_router()` factory from `shared/routes/calendar.py`
+
+## Company Access Validation (2-step)
+1. Check `current_user.companies` (fast, from JWT)
+2. Validate against Oracle DB (authoritative)