Fixes #26035.

Summary

• seed Codex app-server sessions with the current Hermes system/SOUL context on the first turn
• preserve prior text conversation history in that first-turn seed without duplicating the current user message
• add regression coverage for first-turn-only seeding and run_conversation() context projection

Local proof

• python3 -m pytest -o addopts= tests/agent/transports/test_codex_app_server_session.py tests/run_agent/test_codex_app_server_integration.py -q\n- uv run --frozen ruff check run_agent.py agent/transports/codex_app_server_session.py tests/agent/transports/test_codex_app_server_session.py tests/run_agent/test_codex_app_server_integration.py\n- git diff --check\n\n## CI attribution\n- recent company PRs #26068, #26059, and #26038 all show e2e failures, so that lane appears to be preexisting shared baseline noise rather than candidate-specific\n- the broader test lane is mixed across those PRs and is not claimed as baseline for this change