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/pgx/v5/internal/stmtcache/stmtcache.go

@@ -0,0 +1,40 @@
+// Package stmtcache is a cache for statement descriptions.
+package stmtcache
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+
+	"github.com/jackc/pgx/v5/pgconn"
+)
+
+// StatementName returns a statement name that will be stable for sql across multiple connections and program
+// executions.
+func StatementName(sql string) string {
+	digest := sha256.Sum256([]byte(sql))
+	return "stmtcache_" + hex.EncodeToString(digest[0:24])
+}
+
+// Cache caches statement descriptions.
+type Cache interface {
+	// Get returns the statement description for sql. Returns nil if not found.
+	Get(sql string) *pgconn.StatementDescription
+
+	// Put stores sd in the cache. Put panics if sd.SQL is "". Put does nothing if sd.SQL already exists in the cache.
+	Put(sd *pgconn.StatementDescription)
+
+	// Invalidate invalidates statement description identified by sql. Does nothing if not found.
+	Invalidate(sql string)
+
+	// InvalidateAll invalidates all statement descriptions.
+	InvalidateAll()
+
+	// HandleInvalidated returns a slice of all statement descriptions invalidated since the last call to HandleInvalidated.
+	HandleInvalidated() []*pgconn.StatementDescription
+
+	// Len returns the number of cached prepared statement descriptions.
+	Len() int
+
+	// Cap returns the maximum number of cached prepared statement descriptions.
+	Cap() int
+}