- Change comments and commands in new code to use "agent-core"
- Rename OAUTH_DUMMY_KEY to agent-core-oauth-dummy-key
- Add AGENT_CORE_TEST_HOME env var (with OPENCODE_TEST_HOME compat)
- Keep external service URLs (opencode.ai, antigravity.opencode.ai)
- Keep OPENCODE_* flags for upstream compatibility
Part of technical debt cleanup (Phase 7).
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>