feat: Add utilities for working with LocalStack & other tidying

[spompea-cfa]

• Add utilities for working with S3, purging the db, etc.
• Ensure consumer can work with LocalStack's SQS
• Add LOG_LEVEL environment variable
• Add sections to README
• Other tidying, etc.

[Copilot]

Pull Request Overview

This PR adds utilities for working with LocalStack and performs various maintenance tasks. The main purpose is to enable development and testing with LocalStack by providing S3 utilities, configuring LocalStack support in middleware services, and improving logging configuration.

Key changes include:

• Removed outdated test utilities and sample data files
• Added new development scripts for S3 operations and database management
• Enhanced middleware to support LocalStack endpoints and improved logging

Reviewed Changes

Copilot reviewed 14 out of 15 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
middleware/testutils.py	Removed entire file containing old test utilities
middleware/sample-data/	Removed sample data files (customers.jsonl, hemingway.txt)
middleware/loglib.py	Added LOG_LEVEL environment variable support
middleware/consumer.py	Added LocalStack endpoint URL support and reduced log verbosity
middleware/exporter.py	Removed ad-hoc test functions
dev-scripts/	Added new utilities for S3 operations and database purging
docker-compose.yaml	Added LocalStack configuration for tools container
README.md	Major restructuring with LocalStack setup instructions
Dockerfiles	Package installation updates for tools and middleware

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