Add Bruin and ingestr

[arsalann]

Adds two open-source tools to tools.md:

• Pipeline Orchestration: Bruin — Apache-2.0 Go CLI that runs ingestion, SQL/Python transformations, and column-level data quality checks as one pipeline, across BigQuery, Snowflake, Postgres, Redshift, Databricks and DuckDB. ~1.7k stars.
• Data Integration → ELT: ingestr — CLI that copies data between databases, warehouses and SaaS sources with a single command. ~3.8k stars.

Both are actively maintained, neither is currently listed, and the entries match the existing - [Name](repo) - Description. format. Appended to the bottom of their sections; no other lines changed and the table of contents needs no update.

Disclosure: I work on Bruin, so this is a self-submission.