feat: file/screenshot attachments on support tickets (v0.49.1)

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>

apps/web/messages/en.json

@@ -462,6 +462,14 @@
     "titlePlaceholder": "Short summary of the issue or idea",
     "descriptionLabel": "Description",
     "descriptionPlaceholder": "What happened, what you expected, and steps to reproduce (if a bug) — or details on your suggestion/question.",
+    "attachmentsLabel": "Attachments",
+    "attachmentsHint": "Screenshots or files, up to {count}. Images, PDF, text, JSON, or zip — 10MB max each.",
+    "attachmentAdd": "Add file",
+    "attachmentUploading": "Uploading…",
+    "removeAttachment": "Remove attachment",
+    "attachmentLimitReached": "You can attach up to {count} files.",
+    "attachmentTooLarge": "\"{name}\" exceeds the 10MB limit.",
+    "attachmentUploadFailed": "Failed to upload \"{name}\".",
     "submitButton": "Submit",
     "submitting": "Submitting…",
     "submitSuccess": "Thanks! We received your message.",