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/nats-io/nats.go/encoders/builtin/json_enc.go

@@ -0,0 +1,56 @@
+// Copyright 2012-2023 The NATS Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package builtin
+
+import (
+	"encoding/json"
+	"strings"
+)
+
+// JsonEncoder is a JSON Encoder implementation for EncodedConn.
+// This encoder will use the builtin encoding/json to Marshal
+// and Unmarshal most types, including structs.
+type JsonEncoder struct {
+	// Empty
+}
+
+// Encode
+func (je *JsonEncoder) Encode(subject string, v any) ([]byte, error) {
+	b, err := json.Marshal(v)
+	if err != nil {
+		return nil, err
+	}
+	return b, nil
+}
+
+// Decode
+func (je *JsonEncoder) Decode(subject string, data []byte, vPtr any) (err error) {
+	switch arg := vPtr.(type) {
+	case *string:
+		// If they want a string and it is a JSON string, strip quotes
+		// This allows someone to send a struct but receive as a plain string
+		// This cast should be efficient for Go 1.3 and beyond.
+		str := string(data)
+		if strings.HasPrefix(str, `"`) && strings.HasSuffix(str, `"`) {
+			*arg = str[1 : len(str)-1]
+		} else {
+			*arg = str
+		}
+	case *[]byte:
+		*arg = data
+	default:
+		err = json.Unmarshal(data, arg)
+	}
+	return
+}