feat(12.2-02): add file removal, caption, reorder and protected downloads

- DELETE, PUT and POST reorder under .../{id}/files/{field}, each scoped by one parent query (404 for a foreign file)
- protected download and thumb routes: is_public=false only, nosniff, private no-store, sandbox CSP, inline only for jpeg/png/gif/webp
- the save applies deferred removals, replaces attachOne files and rechecks maxFiles and required
- blobs of deleted files are removed after commit
- swagger2openapi emits binary content for file responses
- admin OpenAPI, TS types, conformance, README and attachments docs

internal/tools/swagger2openapi/main_test.go

@@ -234,3 +234,18 @@ func TestConvertFormData(t *testing.T) {
 		t.Fatalf("form schema = %#v", schema)
 	}
 }
+
+func TestConvertFileResponse(t *testing.T) {
+	res := convertResponses(decode(t, `{
+		"200": {"description": "OK", "schema": {"type": "file"}},
+		"404": {"description": "Not Found", "schema": {"$ref": "#/definitions/acme.Error"}}
+	}`), []string{"application/octet-stream"})
+	ok := res["200"].(map[string]any)["content"].(map[string]any)
+	if !reflect.DeepEqual(ok, map[string]any{"application/octet-stream": map[string]any{"schema": map[string]any{"type": "string", "format": "binary"}}}) {
+		t.Fatalf("file response = %#v", ok)
+	}
+	missing := res["404"].(map[string]any)["content"].(map[string]any)
+	if _, ok := missing["application/json"]; !ok || len(missing) != 1 {
+		t.Fatalf("error response next to a binary success = %#v", missing)
+	}
+}