docs: add quickstart code examples for Python, Node.js, PHP and cURL (#9922)

Add examples/quickstart/ with minimal copy-paste scripts that let new
users get a response from a local OmniRoute server in under a minute,
without needing to read the full docs first.

Files added:
- examples/quickstart/python_requests.py  (requests library)
- examples/quickstart/nodejs_axios.js     (axios)
- examples/quickstart/curl_terminal.sh    (bash one-liner)
- examples/quickstart/php_curl.php        (cURL extension)
- examples/quickstart/README.md           (table + key-settings cheatsheet)

README.md: add one sub-line pointer to examples/quickstart/ below the
existing zero-config curl snippet, matching the surrounding <sub> style.

examples/quickstart/python_requests.py

@@ -0,0 +1,28 @@
+"""
+OmniRoute Quickstart — Python (requests library)
+================================================
+Run:  pip install requests  (if not already installed)
+      python python_requests.py
+"""
+
+import requests
+
+# Your local OmniRoute server — started with: npx omniroute
+API_URL = "http://localhost:20128/v1/chat/completions"
+
+headers = {
+    "Content-Type": "application/json",
+    "Authorization": "Bearer dummy-key",  # Any string works for free/keyless providers
+}
+
+data = {
+    "model": "felo/auto",  # Keyless, works out of the box — no sign-up needed
+    "stream": False,
+    "messages": [
+        {"role": "user", "content": "Hello! What can you do?"}
+    ],
+}
+
+response = requests.post(API_URL, headers=headers, json=data)
+response.raise_for_status()
+print(response.json()["choices"][0]["message"]["content"])