feat: Migrate to ultrathin monolith architecture

Consolidate 3 separate applications (reports-app, data-entry-app, telegram-bot) into a unified
architecture with single backend and frontend:

Backend Changes:
- Unified FastAPI backend at backend/ with modular structure
- Modules: reports, data_entry, telegram in backend/modules/
- Centralized config.py and main.py with all routers registered
- Single worker mode (--workers 1) for Telegram bot compatibility
- Shared Oracle connection pool and JWT authentication
- Unified requirements.txt and environment configuration

Frontend Changes:
- Single Vue.js SPA with module-based routing
- Unified frontend at src/ with modules in src/modules/{reports,data-entry}/
- Shared components and stores in src/shared/
- Error boundaries for module isolation
- Dual API proxy in Vite for module communication

Infrastructure:
- New unified startup scripts: start-prod.sh, start-test.sh, start-backend.sh
- Environment templates: .env.dev.example, .env.test.example, .env.prod.example
- Updated deployment scripts for Windows IIS
- Simplified SSH tunnel management

Documentation:
- Comprehensive CLAUDE.md with architecture overview
- Module-specific docs in docs/{data-entry,telegram}/
- Architecture decision records in docs/ARCHITECTURE-DECISIONS.md
- Deployment guides consolidated in deployment/windows/docs/

This migration reduces complexity, improves maintainability, and enables easier
deployment while maintaining all existing functionality.

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

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

backend/modules/reports/services/calendar_service.py

@@ -0,0 +1,77 @@
+"""
+Calendar service for fetching available accounting periods
+"""
+# import sys  # Removed - no longer needed
+import os
+
+from shared.database.oracle_pool import oracle_pool
+from ..models.calendar import CalendarPeriod, CalendarPeriodsResponse
+from ..cache.decorators import cached
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+class CalendarService:
+    """Service for calendar/accounting period operations"""
+
+    # Romanian month names for display
+    MONTH_NAMES_RO = [
+        "Ianuarie", "Februarie", "Martie", "Aprilie", "Mai", "Iunie",
+        "Iulie", "August", "Septembrie", "Octombrie", "Noiembrie", "Decembrie"
+    ]
+
+    @staticmethod
+    @cached(cache_type='schema', key_params=['company_id'])
+    async def _get_schema(company_id: int) -> str:
+        """Get schema for company (CACHED 24h)"""
+        async with oracle_pool.get_connection() as connection:
+            with connection.cursor() as cursor:
+                cursor.execute("""
+                    SELECT schema FROM CONTAFIN_ORACLE.v_nom_firme
+                    WHERE id_firma = :company_id
+                """, {'company_id': company_id})
+                result = cursor.fetchone()
+                return result[0] if result else None
+
+    @staticmethod
+    @cached(cache_type='calendar_periods', key_params=['company_id'])
+    async def get_available_periods(company_id: int) -> CalendarPeriodsResponse:
+        """
+        Get all available accounting periods for a company (CACHED 1h)
+
+        Returns periods ordered by year DESC, month DESC with Romanian month names.
+        """
+        schema = await CalendarService._get_schema(company_id)
+        if not schema:
+            logger.warning(f"Schema not found for company {company_id}")
+            return CalendarPeriodsResponse(periods=[], current_period=None, total_count=0)
+
+        async with oracle_pool.get_connection() as connection:
+            with connection.cursor() as cursor:
+                cursor.execute(f"""
+                    SELECT anul, luna
+                    FROM {schema}.calendar
+                    ORDER BY anul DESC, luna DESC
+                """)
+                rows = cursor.fetchall()
+
+                periods = []
+                for row in rows:
+                    an, luna = row[0], row[1]
+                    month_name = CalendarService.MONTH_NAMES_RO[luna - 1]
+                    periods.append(CalendarPeriod(
+                        an=an,
+                        luna=luna,
+                        display_name=f"{month_name} {an}"
+                    ))
+
+                current_period = periods[0] if periods else None
+
+                logger.info(f"Loaded {len(periods)} accounting periods for company {company_id}")
+
+                return CalendarPeriodsResponse(
+                    periods=periods,
+                    current_period=current_period,
+                    total_count=len(periods)
+                )