refactor: consolidate init scripts and improve infrastructure (#65)

Major infrastructure improvements reducing code duplication and improving maintainability:

## Shared Bash Library
- Create scripts/lib/service-init-common.sh with common Vault AppRole functions
- Refactor all 5 service init scripts (postgres, mysql, redis, mongodb, rabbitmq)
- Reduce ~1600 lines of duplicated code across init scripts
- Fix MySQL JSON parsing: replace fragile grep/sed with jq
- Add support for microdnf/yum package managers (Oracle Linux)

## Docker Compose YAML Anchors
- Add x-redis-common anchor for Redis node configuration
- Add x-redis-exporter-common anchor for Redis exporters
- Reduce ~200 lines of duplicated YAML

## Python Modularization
- Create scripts/devstack/ Python package with type hints
- Modularize into utils.py, vault.py, backup.py modules
- Add comprehensive docstrings and type annotations

## Testing Improvements
- Add parallel test execution (--parallel, --jobs flags)
- Consolidate rollback tests into single parameterized test
- Support basic/standard/comprehensive test levels

## Documentation
- Add Mermaid architecture diagrams to docs/ARCHITECTURE.md
- System overview, startup flow, and network topology diagrams

## Other
- Add configs/network.yaml for centralized network configuration
- Update .gitignore to allow scripts/lib/ directory

All 17 test suites pass (571+ tests).

Author: NormB

.gitignore

@@ -71,6 +71,7 @@ downloads/
 eggs/
 .eggs/
 lib/
+!scripts/lib/
 lib64/
 parts/
 sdist/