Add Cookbook C01-C19 (draft)

docs-src/pages/en/cookbook/c10-stream-response.md

@@ -0,0 +1,52 @@
+---
+title: "C10. Receive a Response as a Stream"
+order: 10
+status: "draft"
+---
+
+To receive a response body chunk by chunk, use a `ContentReceiver`. It's the obvious choice for large files, but it's equally handy for NDJSON (newline-delimited JSON) or log streams where you want to start processing data as it arrives.
+
+## Process each chunk
+
+```cpp
+httplib::Client cli("http://localhost:8080");
+
+auto res = cli.Get("/logs/stream",
+  [](const char *data, size_t len) {
+    std::cout.write(data, len);
+    std::cout.flush();
+    return true; // return false to stop receiving
+  });
+```
+
+Data arrives in the lambda in the order it's received from the server. Return `false` from the callback to stop the download partway through.
+
+## Parse NDJSON line by line
+
+Here's a buffered approach for processing newline-delimited JSON one line at a time.
+
+```cpp
+std::string buffer;
+
+auto res = cli.Get("/events",
+  [&](const char *data, size_t len) {
+    buffer.append(data, len);
+    size_t pos;
+    while ((pos = buffer.find('\n')) != std::string::npos) {
+      auto line = buffer.substr(0, pos);
+      buffer.erase(0, pos + 1);
+      if (!line.empty()) {
+        auto j = nlohmann::json::parse(line);
+        handle_event(j);
+      }
+    }
+    return true;
+  });
+```
+
+Accumulate into a buffer, then pull out and parse one line each time you see a newline. This is the standard pattern for consuming a streaming API in real time.
+
+> **Warning:** When you pass a `ContentReceiver`, `res->body` stays **empty**. Store or process the body inside the callback yourself.
+
+> To track download progress, combine this with C11. Use the Progress Callback.
+> For Server-Sent Events (SSE), see E04. Receive SSE on the Client.