Support form now accepts up to 5 attachments (images, PDF, text, JSON,
zip; 10MB each) via the existing S3/MinIO presigned-upload flow. New
support_ticket_attachments table; attachment links get folded into the
Gitea issue body and shown as thumbnails in both the user's ticket
history and the admin support view.
New presign endpoint (/api/v1/support/attachments/presign, rate-limited
20/hr) scoped to the uploading user rather than a ticket id, since the
ticket doesn't exist yet at upload time.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>