Preserve full BrowserGym observation data in metadata

For VisualWebArena and advanced training scenarios, users may need access
to additional data like timestamps, browser state, or custom fields that
BrowserGym provides.

Changes:
- Store full 'obs' and 'info' dicts from BrowserGym in observation.metadata
- Accessible via metadata['browsergym_obs'] and metadata['browsergym_info']
- Common fields still extracted to top-level for convenience
- Added documentation showing how to access timestamps, DOM objects, etc.

This ensures no information loss while maintaining a clean API.
The environment exposes everything BrowserGym provides - users can access
whatever they need for training.

Author: HamidShojanazeri

src/envs/browsergym_env/README.md

@@ -348,6 +348,33 @@ if obs.last_action_error:
 # Episode status
 print(obs.done)          # True if episode ended
 print(obs.reward)        # Reward for the step
+
+# Access full BrowserGym data (includes timestamps, etc.)
+print(obs.metadata["browsergym_obs"])  # Full observation dict from BrowserGym
+print(obs.metadata["browsergym_info"]) # Full info dict (timestamps, page state, etc.)
+```
+
+#### Advanced: Accessing Raw BrowserGym Data
+
+For VisualWebArena or custom training, you may need additional data like timestamps or browser state. The full BrowserGym observation and info dicts are preserved in `metadata`:
+
+```python
+result = env.step(action)
+
+# Access timestamps (if available)
+info = result.observation.metadata["browsergym_info"]
+if "timestamp" in info:
+    print(f"Action timestamp: {info['timestamp']}")
+
+# Access additional observation fields
+obs_dict = result.observation.metadata["browsergym_obs"]
+if "dom_object" in obs_dict:
+    dom = obs_dict["dom_object"]
+    # Work with raw DOM object
+
+# Access page performance data
+if "performance" in info:
+    print(f"Page load time: {info['performance']}")
 ```
 
 ### State

src/envs/browsergym_env/server/browsergym_environment.py

@@ -219,6 +219,13 @@ def _create_observation(
         axtree_txt = obs.get("axtree_txt", "") if isinstance(obs, dict) else ""
         pruned_html = obs.get("pruned_html", "") if isinstance(obs, dict) else ""
 
+        # Store full BrowserGym observation and info in metadata
+        # This preserves timestamps, additional fields, and any future extensions
+        browsergym_metadata = {
+            "browsergym_obs": obs if isinstance(obs, dict) else {},
+            "browsergym_info": info,
+        }
+
         return BrowserGymObservation(
             text=text,
             url=url,
@@ -230,6 +237,7 @@ def _create_observation(
             last_action_error=False,
             done=done,
             reward=reward,
+            metadata=browsergym_metadata,
         )
 
     @property