feat: add Autotask tags sync (tag groups, tags, ticket tag associations)
- Migration 057: autotask_tag_groups, autotask_tags, and junction tables
(ticket_tags, company_tags, configuration_item_tags, contact_tags)
- Add TAG_GROUPS and TAGS to EntityType enum and dependency map
- Add mapTagGroup() and mapTag() entity mapper functions
- Add syncTagGroups(), syncTags(), syncTicketTagAssociations() methods
- Wire TicketTagAssociations bulk sync into full/incremental sync flow
- Add 'exist' operator to QueryFilter type
- No FK on ticket_id (tagged tickets may be outside 2yr sync window)
Synced: 26 tag groups, 7299 tags, 10141 ticket-tag associations