docs: standardize documentation structure (Phase 1)

Implement Phase 1 of documentation standardization plan:

**New Documentation Structure:**
- docs/README.md - Documentation hub with quick links
- docs/getting-started/ - Installation, prerequisites, quick-start
- docs/deployment/ - Kubernetes, Helm, production guides
- docs/architecture/ - Overview, data-flow, design-decisions, ADR template
- docs/troubleshooting/ - Quick diagnosis, common issues, RBAC, network
- docs/development/ - Testing guide (moved from docs/TESTING.md)

**Granular Breakdown:**
- Split DEPLOYMENT.md → installation.md, kubernetes.md, helm.md, production.md
- Split ARCHITECTURE.md → overview.md, data-flow.md, design-decisions.md
- Split TROUBLESHOOTING.md → README.md, common-issues.md, rbac-issues.md, network-problems.md

**New Content:**
- Quick Start guide (5-minute setup)
- Prerequisites checklist
- Production deployment best practices
- ADR template and index
- Quick diagnosis table

**Updated:**
- README.md now links to new documentation structure
- All documentation cross-referenced with relative links

Implements standardization plan from docs/DOCUMENTATION_STANDARDIZATION_PLAN.md

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

README.md

@@ -172,21 +172,28 @@ Every proxied request is recorded in Kubernetes API audit logs as a `get` on `se
 
 ## Documentation
 
-Comprehensive documentation is available in the `docs/` directory:
+📚 **[Complete Documentation](docs/README.md)** - Documentation hub with all guides
 
-| Document                                          | Description                                                           |
-| ------------------------------------------------- | --------------------------------------------------------------------- |
-| **[ARCHITECTURE.md](docs/ARCHITECTURE.md)**       | System architecture, data flow, component hierarchy, design decisions |
-| **[DEPLOYMENT.md](docs/DEPLOYMENT.md)**           | Complete deployment guide with Helm, FluxCD, RBAC, network policies   |
-| **[SECURITY.md](SECURITY.md)**                    | Security model, RBAC requirements, vulnerability reporting            |
-| **[TROUBLESHOOTING.md](docs/TROUBLESHOOTING.md)** | Common issues, debugging, RBAC testing, network debugging             |
-| **[TESTING.md](docs/TESTING.md)**                 | Unit tests, E2E tests, CI/CD, best practices                          |
-| **[CONTRIBUTING.md](CONTRIBUTING.md)**            | Development workflow, branching strategy, PR process                  |
-| **[CHANGELOG.md](CHANGELOG.md)**                  | Complete release history (v0.0.1 to current)                          |
+### Quick Links
+
+- **[Quick Start](docs/getting-started/quick-start.md)** - Get up and running in 5 minutes
+- **[Installation Guide](docs/getting-started/installation.md)** - All installation methods (Plugin Manager, Sidecar, Manual, Source)
+- **[Troubleshooting](docs/troubleshooting/README.md)** - Quick diagnosis and common issues
+
+### Comprehensive Guides
+
+| Guide | Description |
+|-------|-------------|
+| **[Architecture](docs/architecture/overview.md)** | System architecture, data flow, component hierarchy, design decisions |
+| **[Deployment](docs/deployment/helm.md)** | Production deployment with Helm, Kubernetes, FluxCD |
+| **[Security](SECURITY.md)** | Security model, RBAC requirements, vulnerability reporting |
+| **[Testing](docs/development/testing.md)** | Unit tests, E2E tests, CI/CD, best practices |
+| **[Contributing](CONTRIBUTING.md)** | Development workflow, branching strategy, PR process |
+| **[Changelog](CHANGELOG.md)** | Complete release history (v0.0.1 to current) |
 
 ## Troubleshooting
 
-**For comprehensive troubleshooting, see [docs/TROUBLESHOOTING.md](docs/TROUBLESHOOTING.md).**
+**For comprehensive troubleshooting, see [docs/troubleshooting/README.md](docs/troubleshooting/README.md).**
 
 Quick reference: