feat: re-export widget renderer from bridge

[silversurfer562]

Outcome

Fold PR #60 onto current main without losing the 0.9.0–0.11.1 changelog history.

Changes

• lazily resolve form_to_widget_html from attune_forms.bridge
• preserve the package-root import as preferred
• keep the bridge/widget dependency direction cycle-free
• add the feature only under the current Unreleased changelog section

Receipts

• python -m pytest -p no:cacheprovider -q — 893 passed
• python -m ruff check src tests — passed
• pre-commit Black/Ruff and file hygiene gates — passed

Fold

Supersedes one-commit PR #60, which is DIRTY against current main and carries stale 0.8-era changelog context.