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/jackc/puddle/v2/context.go

@@ -0,0 +1,24 @@
+package puddle
+
+import (
+	"context"
+	"time"
+)
+
+// valueCancelCtx combines two contexts into one. One context is used for values and the other is used for cancellation.
+type valueCancelCtx struct {
+	valueCtx  context.Context
+	cancelCtx context.Context
+}
+
+func (ctx *valueCancelCtx) Deadline() (time.Time, bool) { return ctx.cancelCtx.Deadline() }
+func (ctx *valueCancelCtx) Done() <-chan struct{}       { return ctx.cancelCtx.Done() }
+func (ctx *valueCancelCtx) Err() error                  { return ctx.cancelCtx.Err() }
+func (ctx *valueCancelCtx) Value(key any) any           { return ctx.valueCtx.Value(key) }
+
+func newValueCancelCtx(valueCtx, cancelContext context.Context) context.Context {
+	return &valueCancelCtx{
+		valueCtx:  valueCtx,
+		cancelCtx: cancelContext,
+	}
+}