The a2a completion-bridge tests registered the agent with only
custom_llm_provider and model, so the bridge's litellm.acompletion had no
api_key and relied on the gateway resolving ANTHROPIC_API_KEY from its ambient
env. When that env var is absent, POST /a2a/{id} returns 500 with
"Missing Anthropic API Key" and every message/send test (completion bridge,
pinned v0.3/v1.0 message shapes, semver serves) fails while the
register/discovery/rejection tests still pass.
Give A2ABridgeParams an optional api_key and register the bridge agent with
api_key="os.environ/ANTHROPIC_API_KEY", matching how the rest of the suite
wires anthropic-backed models (e.g. the ratelimit redis tests). The agent now
carries its provider key explicitly instead of depending on ambient gateway env.
Adds get_external to e2e_http.py for absolute third-party GETs (no proxy base url or auth, same Result classification) and rewires fetch_agent_card through it, dropping the urllib.request escape hatch. Creates tests/code_coverage_tests/check_e2e_no_raw_requests.py, the checker tests/e2e/CLAUDE.md already referenced, and wires it into the code-quality workflow so raw HTTP client imports outside the transport fail CI; pre-existing uses (root conftest liveness probe, claude_code version resolver) are grandfathered and exception-type-only imports stay allowed.
