fix(browser): parse DOMShell structured fields for ls and grep

[cat0825]

Description

This PR fixes multiple DOMShell parsing issues introduced in the 2.x migration, addressing both ls and grep formats.

• Updates _parse_execute_result for ls to extract name, role, and path properly, enabling correct JSON round-tripping for follow-up fs commands.
• Updates _parse_execute_result for grep to extract structured fields and adds logic in browser_cli.py to neatly display these elements rather than raw string matching.
• Ensures robust fallback if the format changes upstream.

Fixes #342
Fixes #316

Type of Change

• New Software CLI (in-repo)
• New Software CLI (standalone repo)
• New Feature
• Bug Fix
• Documentation
• Other

---

For Existing CLI Modifications

• All unit tests pass: python3 -m pytest cli_anything/<software>/tests/test_core.py -v
• All E2E tests pass: python3 -m pytest cli_anything/<software>/tests/test_full_e2e.py -v
• No test regressions — no previously passing tests were removed or weakened
• registry.json entry is updated if version, description, or requirements changed

General Checklist

• Code follows existing patterns and conventions
• --json flag is supported on any new commands
• Commit messages follow the conventional format (feat:, fix:, docs:, test:)
• I have tested my changes locally

Test Results

============================= test session starts ==============================
platform darwin -- Python 3.12.2, pytest-7.4.4, pluggy-1.0.0 -- /opt/anaconda3/bin/python
cachedir: .pytest_cache
rootdir: /Users/qianyuhe/研究生生活/CLI-Anything/browser/agent-harness
plugins: anyio-4.14.1
collecting ... 
...
============================= 111 passed in 1.12s ==============================