feat: pre-commit hook to block commits with missing dbt YAML property files

[cbini]

Summary

Add a git pre-commit hook that checks staged .sql files for matching YAML property files.

Motivation

Developers can accidentally commit new SQL models without creating the companion YAML, bypassing contract enforcement entirely. A pre-commit check catches this before the commit lands.

Proposed behavior

• New SQL files: block the commit if no matching YAML exists; instruct the developer to create one first (via the dbt Core Tools extension's "Toggle SQL/Properties" command or manually)
• Modified SQL files: print a non-blocking reminder to run column sync if columns may have changed

Implementation

• Vanilla .git/hooks/pre-commit shell script (not a Trunk action)
• Checks properties/<model>.yml (or .yaml) relative to each staged SQL file
• Covers extracts/ and staging/ model directories

References

• Design spec: docs/superpowers/specs/2026-03-24-dbt-extract-yml-autogen-design.md on branch cbini/feat/claude-dbt-extract-yml-autogen
• Parent issue: feat: dbt YML column sync for extract and staging models dbt-core-tools#12