Reorganize project structure: move docs and scripts to proper directories

Changes:
- Created scripts/ directory for build and utility scripts
- Moved build-for-airgap.sh to scripts/
- Moved check-ready.sh to scripts/
- Kept quickstart scripts in root for easy access
- Moved HELM-DEPLOYMENT.md to docs/

Updated references:
- README.md: Updated link to docs/HELM-DEPLOYMENT.md
- docs/DEPLOYMENT.md: Updated paths to scripts/build-for-airgap.sh
- quickstart-airgap.sh: Updated path to scripts/build-for-airgap.sh
- scripts/check-ready.sh: Updated self-reference path
- helm/warehouse13/QUICKSTART.md: Updated HELM-DEPLOYMENT.md path
- helm/README.md: Updated HELM-DEPLOYMENT.md path

Directory structure now:
/
├── README.md (root)
├── quickstart.sh (root - easy access)
├── quickstart-airgap.sh (root - easy access)
├── docs/ (all documentation)
│   ├── API.md
│   ├── ARCHITECTURE.md
│   ├── DEPLOYMENT.md
│   ├── FEATURES.md
│   ├── FRONTEND_SETUP.md
│   ├── HELM-DEPLOYMENT.md (moved here)
│   └── SUMMARY.md
├── scripts/ (build and utility scripts)
│   ├── build-for-airgap.sh (moved here)
│   └── check-ready.sh (moved here)
└── helm/
    └── warehouse13/ (Helm chart with docs)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

helm/warehouse13/QUICKSTART.md

@@ -118,7 +118,7 @@ kubectl delete namespace warehouse13
 ## Next Steps
 
 - **Full Documentation:** [README.md](./README.md)
-- **Deployment Guide:** [../../HELM-DEPLOYMENT.md](../../HELM-DEPLOYMENT.md)
+- **Deployment Guide:** [../../docs/HELM-DEPLOYMENT.md](../../docs/HELM-DEPLOYMENT.md)
 - **Configuration Options:** [values.yaml](./values.yaml)
 - **Example Configs:** [values-dev.yaml](./values-dev.yaml), [values-production.yaml](./values-production.yaml), [values-airgapped.yaml](./values-airgapped.yaml)