agent-host-e2e-tests

# Agent host end-to-end tests These tests run the whole agent host end-to-end (real server, real bundled provider SDK/CLI, real AHP protocol) while replaying recorded model traffic from committed YAML fixtures — deterministic and tokenless. **Before doing anything, read the architecture + troubleshooting reference:** `src/vs/platform/agentHost/test/node/e2e/README.md` It documents the mental model, the fixture format, every config flag, and a symptom→cause→fix troubleshooting table. This skill is only the *workflows*; the README is the source of truth for *how it works*. ## Non-negotiable rules 1. **Replay is default and strict.** No env var → serves committed fixtures, no token, no network. An unrecorded request is a hard cache miss that fails the run. 2. **A fixture's filename is derived from the test title** (`${provider}-${slug}.yaml`). Renaming a test orphans its fixture — re-record after any rename. 3. **Recording needs a real token** (`GITHUB_TOKEN` or `gh auth token`) and talks to real CAPI. Only run it intentionally, with trivial/read-only prompts in temp dirs. 4. **Never hand-write or hand-edit fixture contents** (especially not secrets/paths). Fixtures are always produced by recording; normalization/redaction is the proxy's job. 5. **Gate, don't fight.** If a behavior can't replay deterministically, gate the test (see Workflow C) instead of loosening timeouts or the strict check. ## Workflow A — Add a cross-provider test 1. Add a `test(...)` to the closest m...