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/golang-migrate/migrate/v4/source/file/README.md

@@ -0,0 +1,4 @@
+# file
+
+`file:///absolute/path`  
+`file://relative/path`

vendor/github.com/golang-migrate/migrate/v4/source/file/file.go

@@ -0,0 +1,66 @@
+package file
+
+import (
+	nurl "net/url"
+	"os"
+	"path/filepath"
+
+	"github.com/golang-migrate/migrate/v4/source"
+	"github.com/golang-migrate/migrate/v4/source/iofs"
+)
+
+func init() {
+	source.Register("file", &File{})
+}
+
+type File struct {
+	iofs.PartialDriver
+	url  string
+	path string
+}
+
+func (f *File) Open(url string) (source.Driver, error) {
+	p, err := parseURL(url)
+	if err != nil {
+		return nil, err
+	}
+	nf := &File{
+		url:  url,
+		path: p,
+	}
+	if err := nf.Init(os.DirFS(p), "."); err != nil {
+		return nil, err
+	}
+	return nf, nil
+}
+
+func parseURL(url string) (string, error) {
+	u, err := nurl.Parse(url)
+	if err != nil {
+		return "", err
+	}
+	// concat host and path to restore full path
+	// host might be `.`
+	p := u.Opaque
+	if len(p) == 0 {
+		p = u.Host + u.Path
+	}
+
+	if len(p) == 0 {
+		// default to current directory if no path
+		wd, err := os.Getwd()
+		if err != nil {
+			return "", err
+		}
+		p = wd
+
+	} else if p[0:1] == "." || p[0:1] != "/" {
+		// make path absolute if relative
+		abs, err := filepath.Abs(p)
+		if err != nil {
+			return "", err
+		}
+		p = abs
+	}
+	return p, nil
+}