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/go-chi/cors/README.md

@@ -0,0 +1,39 @@
+# CORS net/http middleware
+
+[go-chi/cors](https://github.com/go-chi/cors) is a fork of [github.com/rs/cors](https://github.com/rs/cors) that
+provides a `net/http` compatible middleware for performing preflight CORS checks on the server side. These headers
+are required for using the browser native [Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API).
+
+This middleware is designed to be used as a top-level middleware on the [chi](https://github.com/go-chi/chi) router.
+Applying with within a `r.Group()` or using `With()` will not work without routes matching `OPTIONS` added.
+
+## Usage
+
+```go
+func main() {
+  r := chi.NewRouter()
+
+  // Basic CORS
+  // for more ideas, see: https://developer.github.com/v3/#cross-origin-resource-sharing
+  r.Use(cors.Handler(cors.Options{
+    // AllowedOrigins:   []string{"https://foo.com"}, // Use this to allow specific origin hosts
+    AllowedOrigins:   []string{"https://*", "http://*"},
+    // AllowOriginFunc:  func(r *http.Request, origin string) bool { return true },
+    AllowedMethods:   []string{"GET", "POST", "PUT", "DELETE", "OPTIONS"},
+    AllowedHeaders:   []string{"Accept", "Authorization", "Content-Type", "X-CSRF-Token"},
+    ExposedHeaders:   []string{"Link"},
+    AllowCredentials: false,
+    MaxAge:           300, // Maximum value not ignored by any of major browsers
+  }))
+
+  r.Get("/", func(w http.ResponseWriter, r *http.Request) {
+    w.Write([]byte("welcome"))
+  })
+
+  http.ListenAndServe(":3000", r)
+}
+```
+
+## Credits
+
+All credit for the original work of this middleware goes out to [github.com/rs](github.com/rs).