PR Description

This PR introduces a scalable testing and CI/CD foundation for the Balancer dbt connector.
The goal is to make PR approval depend on reliable automated checks.

What was added

• Added a new quality workflow at .github/workflows/dbt_quality.yml.
• This workflow runs on pull requests and executes dbt parse with dependencies.
• It is designed as a zero-credit validation layer.
• Added Husky + lint-staged setup for local pre-commit checks.
• Added package.json and package-lock.json to manage hook tooling.
• Added .husky/pre-commit to run staged validations.
• Added scripts/precommit_dbt_parse.sh to run dbt deps when needed and then dbt parse.

CI behavior updates

• Updated .github/workflows/dbt_ci.yml to run on PR events directly.
• Removed the label gate so integration CI can be required for all PRs.
• Kept workflow_dispatch for manual runs.
• PR integration CI still uses state comparison and incremental validation flow.

Test coverage updates

• Added singular tests for labels category invariants in tests/labels/.
• Added dbt unit tests for v2 and v3 labels union models.
• Added uniqueness data tests for aggregate label models (blockchain, address).
• Extended testing documentation with local vs CI test matrix and unit test guidance.
• Updated CI/CD docs with required checks and branch protection instructions.

This setup supports repo growth by separating fast static checks from Dune integration checks.