fix: handle null ResponseBody source in network interceptor (#107)

- Replace custom ResponseBody anonymous class with ResponseBody.create()
- Ensures valid BufferedSource is returned instead of null
- Prevents NullPointerException when OkHttp attempts to close response
- Fixes crash reported in Google Play Console

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

Author: graycreate

app/src/main/java/me/ghui/v2er/network/APIService.java

@@ -127,23 +127,7 @@ public Response intercept(Chain chain) throws IOException {
                         .protocol(Protocol.HTTP_1_1)
                         .code(404)
                         .message("Exeception when execute chain.proceed request")
-                        .body(new ResponseBody() {
-                            @Nullable
-                            @Override
-                            public MediaType contentType() {
-                                return null;
-                            }
-
-                            @Override
-                            public long contentLength() {
-                                return 0;
-                            }
-
-                            @Override
-                            public BufferedSource source() {
-                                return null;
-                            }
-                        })
+                        .body(ResponseBody.create("Network error occurred", MediaType.parse("text/plain")))
                         .request(request).build();
             }
         }