Fix Zammad ticket sync timeout failures with configurable retry logic

[Copilot]

Zammad worker failing to fetch ticket details with "Request timeout" errors after 30 seconds. Added configurable timeout (default: 60s) and retry logic with exponential backoff.

Changes

• Configurable settings in Settings model:

  • zammad_api_timeout (default: 60s)
  • zammad_max_retries (default: 3)

• Retry logic in ZammadSyncService._make_request():

  • Exponential backoff (1s, 2s, 4s) for Timeout and ConnectionError
  • HTTP errors (4xx/5xx) are not retried

# Before: hardcoded 30s timeout, no retries
REQUEST_TIMEOUT = 30

# After: configurable with retry
self.request_timeout = getattr(settings, 'zammad_api_timeout', 60)
self.max_retries = getattr(settings, 'zammad_max_retries', 3)

for attempt in range(self.max_retries):
    try:
        response = requests.request(..., timeout=self.request_timeout)
    except requests.exceptions.Timeout:
        wait_time = self.RETRY_BACKOFF_FACTOR ** attempt  # 2^attempt
        time.sleep(wait_time)

• Migration: 0058_add_zammad_timeout_and_retry_settings.py
• Tests: 8 new tests for retry behavior
• Docs: Updated ZAMMAD_INTEGRATION_GUIDE.md and ZAMMAD_QUICKREF.md

Original prompt

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This section details on the original issue you should resolve

<issue_title>Failed to fetch details for ticket</issue_title>
<issue_description>Der Zammad Worker, der Ticket aus Zammad abholt und in Ideragraph speichert funktioniert nicht mehr.

Auszug aus dem Logfile:

2025-12-02 10:11:27 [ERROR] [zammad_service] - Failed to fetch details for ticket 78: Request timeout
2025-12-02 10:11:57 [ERROR] [zammad_service] - Failed to fetch details for ticket 1619: Request timeout
2025-12-02 10:12:27 [ERROR] [zammad_service] - Failed to fetch details for ticket 1534: Request timeout

Mehr Fehlerinformationen liegen leider nicht vor.</issue_description>

Comments on the Issue (you are @copilot in this section)

@gdsanger Created with IdeaGraph v1.0

Task: http://idea.angermeier.net/tasks/084dbedb-6434-47f1-9bab-9e7ce2826f71</comment_new>

• Fixes Failed to fetch details for ticket #723

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