feat: add Agent Skills and restructure documentation

- Add 47 Agent Skills across 14 plugins following Anthropic's specification
  - Python (5): async patterns, testing, packaging, performance, UV package manager
  - JavaScript/TypeScript (4): advanced types, Node.js patterns, testing, modern JS
  - Kubernetes (4): manifests, Helm charts, GitOps, security policies
  - Cloud Infrastructure (4): Terraform, multi-cloud, hybrid networking, cost optimization
  - CI/CD (4): pipeline design, GitHub Actions, GitLab CI, secrets management
  - Backend (3): API design, architecture patterns, microservices
  - LLM Applications (4): LangChain, prompt engineering, RAG, evaluation
  - Blockchain/Web3 (4): DeFi protocols, NFT standards, Solidity security, Web3 testing
  - Framework Migration (4): React, Angular, database, dependency upgrades
  - Observability (4): Prometheus, Grafana, distributed tracing, SLO
  - Payment Processing (4): Stripe, PayPal, PCI compliance, billing
  - API Scaffolding (1): FastAPI templates
  - ML Operations (1): ML pipeline workflow
  - Security (1): SAST configuration

- Restructure documentation into /docs directory
  - agent-skills.md: Complete guide to all 47 skills
  - agents.md: All 85 agents with model configuration
  - plugins.md: Complete catalog of 63 plugins
  - usage.md: Commands, workflows, and best practices
  - architecture.md: Design principles and patterns

- Update README.md
  - Add Agent Skills banner announcement
  - Reduce length by ~75% with links to detailed docs
  - Add What's New section showcasing Agent Skills
  - Add Popular Use Cases with real examples
  - Improve navigation with Core Guides and Quick Links

- Update marketplace.json with skills arrays for 14 plugins

All 47 skills follow Agent Skills Specification:
- Required YAML frontmatter (name, description)
- Use when activation clauses
- Progressive disclosure architecture
- Under 1024 character descriptions

plugins/kubernetes-operations/skills/gitops-workflow/references/sync-policies.md

@@ -0,0 +1,131 @@
+# GitOps Sync Policies
+
+## ArgoCD Sync Policies
+
+### Automated Sync
+```yaml
+syncPolicy:
+  automated:
+    prune: true       # Delete resources removed from Git
+    selfHeal: true    # Reconcile manual changes
+    allowEmpty: false # Prevent empty sync
+```
+
+### Manual Sync
+```yaml
+syncPolicy:
+  syncOptions:
+  - PrunePropagationPolicy=foreground
+  - CreateNamespace=true
+```
+
+### Sync Windows
+```yaml
+syncWindows:
+- kind: allow
+  schedule: "0 8 * * *"
+  duration: 1h
+  applications:
+  - my-app
+- kind: deny
+  schedule: "0 22 * * *"
+  duration: 8h
+  applications:
+  - '*'
+```
+
+### Retry Policy
+```yaml
+syncPolicy:
+  retry:
+    limit: 5
+    backoff:
+      duration: 5s
+      factor: 2
+      maxDuration: 3m
+```
+
+## Flux Sync Policies
+
+### Kustomization Sync
+```yaml
+apiVersion: kustomize.toolkit.fluxcd.io/v1
+kind: Kustomization
+metadata:
+  name: my-app
+spec:
+  interval: 5m
+  prune: true
+  wait: true
+  timeout: 5m
+  retryInterval: 1m
+  force: false
+```
+
+### Source Sync Interval
+```yaml
+apiVersion: source.toolkit.fluxcd.io/v1
+kind: GitRepository
+metadata:
+  name: my-app
+spec:
+  interval: 1m
+  timeout: 60s
+```
+
+## Health Assessment
+
+### Custom Health Checks
+```yaml
+# ArgoCD
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: argocd-cm
+  namespace: argocd
+data:
+  resource.customizations.health.MyCustomResource: |
+    hs = {}
+    if obj.status ~= nil then
+      if obj.status.conditions ~= nil then
+        for i, condition in ipairs(obj.status.conditions) do
+          if condition.type == "Ready" and condition.status == "False" then
+            hs.status = "Degraded"
+            hs.message = condition.message
+            return hs
+          end
+          if condition.type == "Ready" and condition.status == "True" then
+            hs.status = "Healthy"
+            hs.message = condition.message
+            return hs
+          end
+        end
+      end
+    end
+    hs.status = "Progressing"
+    hs.message = "Waiting for status"
+    return hs
+```
+
+## Sync Options
+
+### Common Sync Options
+- `PrunePropagationPolicy=foreground` - Wait for pruned resources to be deleted
+- `CreateNamespace=true` - Auto-create namespace
+- `Validate=false` - Skip kubectl validation
+- `PruneLast=true` - Prune resources after sync
+- `RespectIgnoreDifferences=true` - Honor ignore differences
+- `ApplyOutOfSyncOnly=true` - Only apply out-of-sync resources
+
+## Best Practices
+
+1. Use automated sync for non-production
+2. Require manual approval for production
+3. Configure sync windows for maintenance
+4. Implement health checks for custom resources
+5. Use selective sync for large applications
+6. Configure appropriate retry policies
+7. Monitor sync failures with alerts
+8. Use prune with caution in production
+9. Test sync policies in staging
+10. Document sync behavior for teams