Fix D1 constraint reflection

[CollierKing]

Summary

Fixes the two D1 reflection gaps called out in PR #26 and prepares the patch release that includes the composite primary-key fix.

• Adds referred_schema to foreign key reflection results.
• Implements get_unique_constraints() for inline and named table-level unique constraints.
• Keeps explicit unique indexes reflected through get_indexes() rather than unique constraint reflection.
• Adds unit, REST API integration, and Worker integration coverage for constraint reflection.
• Bumps the package version and changelog to 0.3.11 to include the composite primary-key DDL fix plus these reflection fixes.

Validation

• uv run ruff format . --diff
• uv run ruff check .
• uv run mypy src/
• uv run pytest --disable-socket --allow-unix-socket tests/ -q -> 24 passed
• REST API integration file -> 81 passed
• Worker integration file with Node v22.17.1 on PATH -> 66 passed
• uv build
• uv run pre-commit run --all-files