feat(sub): allow identity tokens on every subscription link (#5935)

Keep usage tokens first-link-only while adding an opt-in setting for repeating EMAIL and USERNAME in subscription-body remarks.

Co-authored-by: x06579 <x06579@ai-dashboard>

internal/sub/remark_vars.go

@@ -560,7 +560,11 @@ func (s *SubService) effectiveTemplate(email string) string {
 		s.usageShown = map[string]bool{}
 	}
 	if s.usageShown[email] {
-		return filterRemarkTemplate(translated, firstLinkOnlyBodyTokens)
+		remove := firstLinkOnlyBodyTokens
+		if s.showIdentityOnAllLinks {
+			remove = usageInfoTokens
+		}
+		return filterRemarkTemplate(translated, remove)
 	}
 	s.usageShown[email] = true
 	return translated