feat(12.2-02): add the fileupload field with deferred uploads committed on save

- type: fileupload compiles the D-08 keys and binds to the model's attach.Relation at boot
- X-Session-Key (cabana.SessionKeyHeader) carries the form session key; RecordInput.SessionKey
- GET and POST .../{id}/files/{field}: list with pending uploads, multipart upload into attach.Store
- the create and update save attaches the session's pending files in its transaction
- swagger2openapi folds formData parameters into a multipart requestBody
- admin OpenAPI, TS types, conformance cases, README and forms docs

internal/tools/swagger2openapi/main_test.go

@@ -201,3 +201,36 @@ func TestMalformedShapesPassThrough(t *testing.T) {
 		t.Fatalf("foreign ref rewritten: %v", got)
 	}
 }
+
+func TestConvertFormData(t *testing.T) {
+	op := decode(t, `{
+		"consumes": ["multipart/form-data"],
+		"parameters": [
+			{"name": "id", "in": "path", "required": true, "type": "integer"},
+			{"name": "file_data", "in": "formData", "required": true, "type": "file", "description": "The file"},
+			{"name": "note", "in": "formData", "type": "string"}
+		],
+		"responses": {"201": {"description": "Created"}}
+	}`)
+	out := convertOperation(op, nil, nil)
+	params := out["parameters"].([]any)
+	if len(params) != 1 || params[0].(map[string]any)["name"] != "id" {
+		t.Fatalf("parameters = %#v", params)
+	}
+	body := out["requestBody"].(map[string]any)
+	if body["required"] != true {
+		t.Fatalf("request body = %#v", body)
+	}
+	schema := body["content"].(map[string]any)["multipart/form-data"].(map[string]any)["schema"].(map[string]any)
+	want := map[string]any{
+		"type": "object",
+		"properties": map[string]any{
+			"file_data": map[string]any{"type": "string", "format": "binary", "description": "The file"},
+			"note":      map[string]any{"type": "string"},
+		},
+		"required": []any{"file_data"},
+	}
+	if !reflect.DeepEqual(schema, want) {
+		t.Fatalf("form schema = %#v", schema)
+	}
+}