feat: add cross-asset volatility ratio metric

[C00ldudeNoonan]

Summary

• Add a cross-asset semantic model for shared volatility ratio queries across stocks, sector ETFs, and input commodities
• Wire existing annualized_volatility_ratio through unique cross-asset measures to satisfy Semantic Layer constraints
• Add the shared metric to sector and commodity saved queries
• Clean up dbt/SQLFluff lint caveats so make lint and parse are usable gates

Validation

• make lint
• make dbt-manifest
• dbt run --select cross_asset_daily_volatility
• dbt test --select cross_asset_daily_volatility (4/4 pass in dev)

Fixes #106

[C00ldudeNoonan]

@codex please review this PR.