Add calendar sync utilities and Beteiligte sync cron job

- Implemented calendar_sync_utils.py for shared utility functions
  including DB connection, Google Calendar service initialization,
  Redis client setup, and employee sync operations.

- Created beteiligte_sync_cron_step.py to handle periodic sync
  of Beteiligte entities, checking for new, modified, failed,
  and stale records, and emitting sync events accordingly.

steps/advoware_cal_sync/calendar_sync_all_step.py

@@ -0,0 +1,113 @@
+"""
+Calendar Sync All Step
+
+Handles calendar_sync_all event and emits individual sync events for oldest employees.
+Uses Redis to track last sync times and distribute work.
+"""
+import sys
+from pathlib import Path
+sys.path.insert(0, str(Path(__file__).parent))
+from calendar_sync_utils import (
+    get_redis_client, 
+    get_advoware_employees, 
+    set_employee_lock, 
+    log_operation
+)
+
+import math
+import time
+from datetime import datetime
+from typing import Any
+from motia import queue, FlowContext
+from pydantic import BaseModel, Field
+from services.advoware_service import AdvowareService
+
+config = {
+    'name': 'Calendar Sync All Step',
+    'description': 'Receives sync-all event and emits individual events for oldest employees',
+    'flows': ['advoware'],
+    'triggers': [
+        queue('calendar_sync_all')
+    ],
+    'enqueues': ['calendar_sync_employee']
+}
+
+
+async def handler(input_data: dict, ctx: FlowContext):
+    """
+    Handler that fetches all employees, sorts by last sync time,
+    and emits calendar_sync_employee events for the oldest ones.
+    """
+    try:
+        triggered_by = input_data.get('triggered_by', 'unknown')
+        log_operation('info', f"Calendar Sync All: Starting to emit events for oldest employees, triggered by {triggered_by}", context=ctx)
+
+        # Initialize Advoware service
+        advoware = AdvowareService(ctx)
+
+        # Fetch employees
+        employees = await get_advoware_employees(advoware, ctx)
+        if not employees:
+            log_operation('error', "Keine Mitarbeiter gefunden. All-Sync abgebrochen.", context=ctx)
+            return {'status': 500, 'body': {'error': 'Keine Mitarbeiter gefunden'}}
+
+        redis_client = get_redis_client(ctx)
+
+        # Collect last_synced timestamps
+        employee_timestamps = {}
+        for employee in employees:
+            kuerzel = employee.get('kuerzel')
+            if not kuerzel:
+                continue
+            employee_last_synced_key = f'calendar_sync_last_synced_{kuerzel}'
+            timestamp_str = redis_client.get(employee_last_synced_key)
+            timestamp = int(timestamp_str) if timestamp_str else 0  # 0 if no timestamp (very old)
+            employee_timestamps[kuerzel] = timestamp
+
+        # Sort employees by last_synced (ascending, oldest first), then by kuerzel alphabetically
+        sorted_kuerzel = sorted(employee_timestamps.keys(), key=lambda k: (employee_timestamps[k], k))
+
+        # Log the sorted list with timestamps
+        def format_timestamp(ts):
+            if ts == 0:
+                return "never"
+            return datetime.fromtimestamp(ts).strftime('%Y-%m-%d %H:%M:%S')
+        
+        sorted_list_str = ", ".join(f"{k} ({format_timestamp(employee_timestamps[k])})" for k in sorted_kuerzel)
+        log_operation('info', f"Calendar Sync All: Sorted employees by last synced: {sorted_list_str}", context=ctx)
+
+        # Calculate number to sync: ceil(N / 10)
+        num_to_sync = math.ceil(len(sorted_kuerzel) / 1)
+        log_operation('info', f"Calendar Sync All: Total employees {len(sorted_kuerzel)}, syncing {num_to_sync} oldest", context=ctx)
+
+        # Emit for the oldest num_to_sync employees, if not locked
+        emitted_count = 0
+        for kuerzel in sorted_kuerzel[:num_to_sync]:
+            if not set_employee_lock(redis_client, kuerzel, triggered_by, ctx):
+                log_operation('info', f"Calendar Sync All: Sync already active for {kuerzel}, skipping", context=ctx)
+                continue
+
+            # Emit event for this employee
+            await ctx.enqueue({
+                "topic": "calendar_sync_employee",
+                "data": {
+                    "kuerzel": kuerzel,
+                    "triggered_by": triggered_by
+                }
+            })
+            log_operation('info', f"Calendar Sync All: Emitted event for employee {kuerzel} (last synced: {format_timestamp(employee_timestamps[kuerzel])})", context=ctx)
+            emitted_count += 1
+
+        log_operation('info', f"Calendar Sync All: Completed, emitted {emitted_count} events", context=ctx)
+        return {
+            'status': 'completed',
+            'triggered_by': triggered_by,
+            'emitted_count': emitted_count
+        }
+
+    except Exception as e:
+        log_operation('error', f"Fehler beim All-Sync: {e}", context=ctx)
+        return {
+            'status': 'error',
+            'error': str(e)
+        }