- Fix error handling in SignatureManager load/save/delete to extract message from ApiError
- Same pattern as sync fix: err?.message || err?.detail instead of String(err)
- Replace textarea in SignatureManager with TipTap RichTextEditor
- Add placeholder variable buttons: {{user.name}}, {{user.first_name}},
{{user.last_name}}, {{user.email}}, {{user.role}}, {{tenant.name}}, {{date}}
- Add replaceSignatureVariables() utility in mail API
- ComposeModal now replaces variables with actual user/tenant data when inserting signature
- Variables resolved from auth store (user name, email, role, tenant name)