feat: add network request detail and filtering for request tracking (#935)

* feat: add network request detail and filtering for request tracking

- Add `network request <requestId>` command to view full request/response
  details including response body via CDP Network.getResponseBody
- Add --type, --method, --status filter flags to `network requests`
  - --type: comma-separated resource types (xhr,fetch,document)
  - --method: filter by HTTP method
  - --status: supports exact (200), class (2xx), range (400-499)
- Extend TrackedRequest with request_id, post_data, status,
  response_headers, mime_type fields
- Update Network.responseReceived handler to also populate
  tracked_requests (previously only updated HAR entries)
- Add tests for parse commands and matches_status_filter
- Update README, SKILL.md, docs, and help text

Closes #932

* fix: show request ID and status in network requests output

README.md

@@ -270,6 +270,10 @@ agent-browser network route <url> --body <json>  # Mock response
 agent-browser network unroute [url]            # Remove routes
 agent-browser network requests                 # View tracked requests
 agent-browser network requests --filter api    # Filter requests
+agent-browser network requests --type xhr,fetch  # Filter by resource type
+agent-browser network requests --method POST   # Filter by HTTP method
+agent-browser network requests --status 2xx    # Filter by status (200, 2xx, 400-499)
+agent-browser network request <requestId>      # View full request/response detail
 agent-browser network har start                # Start HAR recording
 agent-browser network har stop [output.har]    # Stop and save HAR (temp path if omitted)
 ```