[binaryaaron]

Related issue

Replaces #45 with a descriptive branch name. Intended for squash merge.

What changed and why

Start UserSim 0.3 development at 0.3.0.dev0, move supported Python versions to >=3.11,<3.15, and require released data-designer>=0.10,<0.11. Python 3.10 users remain on the 0.2 release line. Python 3.12 remains the development default; the CI matrix, compatibility imports/dependencies, documentation, and packaging checks follow the new supported range.

Keep main's uv>=0.13.4 minimum and existing setup commands. UV_FROZEN is removed. The lock uses all three DD packages at 0.10.0 from PyPI, with no temporary Git overrides or no-sources. DD engine's new minimum also requires a newer json-repair.

How it was verified

• 247 focused tests passed on Python 3.11.13 across packaging, CI workflows, network isolation, CLI, model catalog, and model facades. Locked installation confirmed all three DD packages at registry version 0.10.0.
• Lock consistency, documentation links, and whitespace checks passed. Changed-file Ruff lint/format passed before the metadata-only DD release follow-up.
• Full make check-dist passed on Python 3.12, including archive/Twine checks, clean registry wheel installation outside the checkout, installed smoke, and simulation dry-run.
• Independent Sol high review found no blocking issues.

The full suite/matrix, container, and live-provider checks were not rerun locally for the released-DD revision. CI results for this PR will establish its remote status. Existing dependent PRs remain stacked; #46 targets this branch.