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/opencontainers/go-digest/verifiers.go

@@ -0,0 +1,46 @@
+// Copyright 2019, 2020 OCI Contributors
+// Copyright 2017 Docker, Inc.
+//
+// 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
+//
+//     https://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 digest
+
+import (
+	"hash"
+	"io"
+)
+
+// Verifier presents a general verification interface to be used with message
+// digests and other byte stream verifications. Users instantiate a Verifier
+// from one of the various methods, write the data under test to it then check
+// the result with the Verified method.
+type Verifier interface {
+	io.Writer
+
+	// Verified will return true if the content written to Verifier matches
+	// the digest.
+	Verified() bool
+}
+
+type hashVerifier struct {
+	digest Digest
+	hash   hash.Hash
+}
+
+func (hv hashVerifier) Write(p []byte) (n int, err error) {
+	return hv.hash.Write(p)
+}
+
+func (hv hashVerifier) Verified() bool {
+	return hv.digest == NewDigest(hv.digest.Algorithm(), hv.hash)
+}