Release 0.3.11

[Lucenx9]

Summary

• bump package version to 0.3.11
• promote the current unreleased changes into the 0.3.11 changelog entry
• keep README unchanged because the tested command surface already matches the docs

Verification

• ~/.local/bin/ruff check agentinit tests cli
• python3 -m pytest tests/ -q
• smoke tests for init/minimal/new/add/remove/status/sync/lint/refresh-llms
• .venv/bin/python -m build --no-isolation
• .venv/bin/python -m twine check --strict <0.3.11 artifacts>
• offline wheel install smoke test in a fresh venv