#281: /raw streams attachment blob for all attachment mimes

handleRaw only streamed the blob behind an isImageMime gate (#221), so
non-image attachment pastes fell through to empty row.Content and /raw
served 0 bytes. Serve the blob for every attachment mime, passing the
sniffed mime through serveContentType so active-content types (html,
svg, xml) still serve as text/plain per the #34 rule. Regression tests
cover text and html attachments (size, Content-Type, byte equality).

internal/api/server.go

@@ -496,15 +496,18 @@ func (a *apiServer) handleRaw(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "not found", 404)
 		return
 	}
-	// #221: raw view of an image paste serves the image bytes themselves as
-	// an image, not the (empty) text content.
-	if att, err := a.store.GetAttachmentForPaste(row.ID); err == nil && att != nil && isImageMime(att.Mime) {
+	// #221: raw view of a paste backed by an attachment serves the stored
+	// blob bytes with the sniffed mime, not the (empty) text content — for
+	// ALL attachment mimes (#281); /raw/{id} is the raw fetch for the file
+	// too. serveContentType still forces active-content types (html, svg,
+	// xml) to text/plain per the #34 rule below.
+	if att, err := a.store.GetAttachmentForPaste(row.ID); err == nil && att != nil {
 		blobs := a.store.Blobs()
 		if blobs != nil {
 			if blob, err := blobs.Get(row.ID + "/" + att.SHA256); err == nil {
 				defer blob.Close()
 				a.store.IncrementViews(row.ID, "", 0) // raw views always count (#49/#95)
-				w.Header().Set("Content-Type", att.Mime)
+				w.Header().Set("Content-Type", serveContentType(att.Mime))
 				w.Header().Set("X-Content-Type-Options", "nosniff")
 				w.Header().Set("Content-Length", fmt.Sprintf("%d", att.Size))
 				http.ServeContent(w, r, "", time.Unix(att.CreatedAt, 0), blob)