docs: refresh aiograpi roadmap

[subzeroid]

Summary

• bump optional aiograpi extra and lockfile to aiograpi 0.9.6
• refresh current docs/code comments so aiograpi is no longer described as a future v0.2 backend
• add a tracked Roadmap page for aiograpi 0.9.x follow-ups: read-only Direct inbox, saved collections/feed audit, and private GraphQL pagination audit

Sources checked

• PyPI: https://pypi.org/project/aiograpi/
• aiograpi 0.9.6 release: https://github.com/subzeroid/aiograpi/releases/tag/0.9.6
• aiograpi docs: https://subzeroid.github.io/aiograpi/latest/

Verification

• uv run --extra aiograpi python -c '<aiograpi 0.9.6 signature check>'
• uv run --extra aiograpi pytest tests/test_aiograpi_map.py tests/test_backend_contract.py tests/test_commands_discovery.py tests/test_config.py
• uv run pytest
• uv run ruff check .
• uv run --extra docs mkdocs build --strict --site-dir /tmp/insto-mkdocs-site
• uv run mypy insto

Note

• uv run mypy insto tests still reports existing test-suite typing issues unrelated to this branch; production package mypy passes.