chore: release v0.7.0 contracts pack, schema-snapshot, validate-contract

[Pawansingh3889]

What changed

Cuts v0.7.0 to PyPI. This is the headline release for the Contracts theme: schema-aware linting via the new C001-C005 rule pack, two new CLI subcommands (schema-snapshot, validate-contract), and three community-contributed rules (W014 / W015 / W022).

Headline features

Area	Change
Contracts pack	New --contract path.yml flag enables 5 schema-aware rules (C001-C005). Without it, behaviour is identical to v0.6.x
schema-snapshot	Bootstrap a contract from a live database via SQLAlchemy introspection. Requires pip install "sql-sop[snapshot]"
validate-contract	Validate the YAML before running rules. CI-friendly, exits non-zero on parse failure
W014 case-without-else	Walks CASE/END token-by-token. Contributed by @hellozzm (#32)
W015 join-function-on-column	JOIN-side companion to W003. Contributed by @mvanhorn (#33)
W022 cross-join-explicit	Flags explicit CROSS JOIN. Contributed by @vibeyclaw (#31)

Rule counts

• Core registry: 43 rules (10 errors, 28 warnings, 5 Python-source)
• With --contract: 48 rules (12 errors, 31 warnings, 5 Python-source)

Backwards compatibility

No breaking changes. All Contracts-pack rules require an explicit --contract flag (or contract: field in .sql-guard.yml); silent without it.

Files in this PR

• pyproject.toml: 0.6.2 → 0.7.0
• CHANGELOG.md: cut [Unreleased] → [0.7.0] - 2026-05-02 with headline summary
• README.md: bumped Version, Tests count (152 → 210), pre-commit rev pin (v0.6.2 → v0.7.0), description text
• .pre-commit-config.yaml: self-reference rev pin (v0.6.2 → v0.7.0)
• ROADMAP.md: refreshed Current release section to point at v0.7.0

Tests

• pytest: 209 passed, 1 skipped
• ruff check: clean

Next steps after merge

1. Tag v0.7.0 on main
2. Push tag to trigger the release workflow (Trusted Publishing to PyPI)
3. Verify on https://pypi.org/project/sql-sop/0.7.0/
4. Create GitHub Release with the CHANGELOG body
5. Update any downstream consumers (sql-sop-mcp, dependent projects) to require >=0.7.0 if they want the contract loader API