Rename directories to plural form: skill/ → skills/, agent/ → agents/, command/ → commands/

- Rename skill/ to skills/ for consistency with naming conventions
- Rename agent/ to agents/ and command/ to commands/
- Update AGENTS.md with all directory references
- Update scripts/test-skill.sh paths
- Update prompts/athena.txt documentation

This aligns with best practices of using plural directory names and updates
all documentation to reflect the new structure.

skills/excalidraw/references/colors.md

@@ -0,0 +1,91 @@
+# Color Palettes Reference
+
+Color schemes for different platforms and component types.
+
+---
+
+## Default Palette (Platform-Agnostic)
+
+| Component Type | Background | Stroke | Example |
+|----------------|------------|--------|---------|
+| Frontend/UI | `#a5d8ff` | `#1971c2` | Next.js, React apps |
+| Backend/API | `#d0bfff` | `#7048e8` | API servers, processors |
+| Database | `#b2f2bb` | `#2f9e44` | PostgreSQL, MySQL, MongoDB |
+| Storage | `#ffec99` | `#f08c00` | Object storage, file systems |
+| AI/ML Services | `#e599f7` | `#9c36b5` | ML models, AI APIs |
+| External APIs | `#ffc9c9` | `#e03131` | Third-party services |
+| Orchestration | `#ffa8a8` | `#c92a2a` | Workflows, schedulers |
+| Validation | `#ffd8a8` | `#e8590c` | Validators, checkers |
+| Network/Security | `#dee2e6` | `#495057` | VPC, IAM, firewalls |
+| Classification | `#99e9f2` | `#0c8599` | Routers, classifiers |
+| Users/Actors | `#e7f5ff` | `#1971c2` | User ellipses |
+| Message Queue | `#fff3bf` | `#fab005` | Kafka, RabbitMQ, SQS |
+| Cache | `#ffe8cc` | `#fd7e14` | Redis, Memcached |
+| Monitoring | `#d3f9d8` | `#40c057` | Prometheus, Grafana |
+
+---
+
+## AWS Palette
+
+| Service Category | Background | Stroke |
+|-----------------|------------|--------|
+| Compute (EC2, Lambda, ECS) | `#ff9900` | `#cc7a00` |
+| Storage (S3, EBS) | `#3f8624` | `#2d6119` |
+| Database (RDS, DynamoDB) | `#3b48cc` | `#2d3899` |
+| Networking (VPC, Route53) | `#8c4fff` | `#6b3dcc` |
+| Security (IAM, KMS) | `#dd344c` | `#b12a3d` |
+| Analytics (Kinesis, Athena) | `#8c4fff` | `#6b3dcc` |
+| ML (SageMaker, Bedrock) | `#01a88d` | `#017d69` |
+
+---
+
+## Azure Palette
+
+| Service Category | Background | Stroke |
+|-----------------|------------|--------|
+| Compute | `#0078d4` | `#005a9e` |
+| Storage | `#50e6ff` | `#3cb5cc` |
+| Database | `#0078d4` | `#005a9e` |
+| Networking | `#773adc` | `#5a2ca8` |
+| Security | `#ff8c00` | `#cc7000` |
+| AI/ML | `#50e6ff` | `#3cb5cc` |
+
+---
+
+## GCP Palette
+
+| Service Category | Background | Stroke |
+|-----------------|------------|--------|
+| Compute (GCE, Cloud Run) | `#4285f4` | `#3367d6` |
+| Storage (GCS) | `#34a853` | `#2d8e47` |
+| Database (Cloud SQL, Firestore) | `#ea4335` | `#c53929` |
+| Networking | `#fbbc04` | `#d99e04` |
+| AI/ML (Vertex AI) | `#9334e6` | `#7627b8` |
+
+---
+
+## Kubernetes Palette
+
+| Component | Background | Stroke |
+|-----------|------------|--------|
+| Pod | `#326ce5` | `#2756b8` |
+| Service | `#326ce5` | `#2756b8` |
+| Deployment | `#326ce5` | `#2756b8` |
+| ConfigMap/Secret | `#7f8c8d` | `#626d6e` |
+| Ingress | `#00d4aa` | `#00a888` |
+| Node | `#303030` | `#1a1a1a` |
+| Namespace | `#f0f0f0` | `#c0c0c0` (dashed) |
+
+---
+
+## Diagram Type Suggestions
+
+| Diagram Type | Recommended Layout | Key Elements |
+|--------------|-------------------|--------------|
+| Microservices | Vertical flow | Services, databases, queues, API gateway |
+| Data Pipeline | Horizontal flow | Sources, transformers, sinks, storage |
+| Event-Driven | Hub-and-spoke | Event bus center, producers/consumers |
+| Kubernetes | Layered groups | Namespace boxes, pods inside deployments |
+| CI/CD | Horizontal flow | Source -> Build -> Test -> Deploy -> Monitor |
+| Network | Hierarchical | Internet -> LB -> VPC -> Subnets -> Instances |
+| User Flow | Swimlanes | User actions, system responses, external calls |