[codex] Add Browserbase Doctor skill

[shubh24]

What changed

• adds the browserbase-doctor skill for read-only session diagnosis
• adds a stdlib-only CLI supporting live Browserbase API collection and offline JSON exports
• classifies lifecycle, network, page, CAPTCHA, client-timeout, rate-limit, and concurrency signals
• redacts API keys, connection URLs, credentials, headers, request bodies, and URL query values
• documents the supported public API surface, evidence limits, and confidence rules
• adds focused tests and lists the skill in the repository README

Why

Customers often have a Browserbase session ID but need to correlate session lifecycle, CDP logs, and their own automation exception to understand what failed. This provides a repeatable diagnostic workflow while keeping credentials and customer data out of reports.

Validation

• python3 skills/browserbase-doctor/tests/test_browserbase_doctor.py
• quick_validate.py skills/browserbase-doctor
• git diff --cached --check
• secret-pattern scan across the new skill