feat: Production readiness improvements for WHOOSH council formation

Major security, observability, and configuration improvements:

## Security Hardening
- Implemented configurable CORS (no more wildcards)
- Added comprehensive auth middleware for admin endpoints
- Enhanced webhook HMAC validation
- Added input validation and rate limiting
- Security headers and CSP policies

## Configuration Management
- Made N8N webhook URL configurable (WHOOSH_N8N_BASE_URL)
- Replaced all hardcoded endpoints with environment variables
- Added feature flags for LLM vs heuristic composition
- Gitea fetch hardening with EAGER_FILTER and FULL_RESCAN options

## API Completeness
- Implemented GetCouncilComposition function
- Added GET /api/v1/councils/{id} endpoint
- Council artifacts API (POST/GET /api/v1/councils/{id}/artifacts)
- /admin/health/details endpoint with component status
- Database lookup for repository URLs (no hardcoded fallbacks)

## Observability & Performance
- Added OpenTelemetry distributed tracing with goal/pulse correlation
- Performance optimization database indexes
- Comprehensive health monitoring
- Enhanced logging and error handling

## Infrastructure
- Production-ready P2P discovery (replaces mock implementation)
- Removed unused Redis configuration
- Enhanced Docker Swarm integration
- Added migration files for performance indexes

## Code Quality
- Comprehensive input validation
- Graceful error handling and failsafe fallbacks
- Backwards compatibility maintained
- Following security best practices

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

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

vendor/github.com/docker/go-connections/tlsconfig/config_client_ciphers.go

@@ -0,0 +1,17 @@
+// +build go1.5
+
+// Package tlsconfig provides primitives to retrieve secure-enough TLS configurations for both clients and servers.
+//
+package tlsconfig
+
+import (
+	"crypto/tls"
+)
+
+// Client TLS cipher suites (dropping CBC ciphers for client preferred suite set)
+var clientCipherSuites = []uint16{
+	tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
+	tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
+	tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
+	tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
+}