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-jwt/jwt/v5/ecdsa.go

@@ -0,0 +1,134 @@
+package jwt
+
+import (
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/rand"
+	"errors"
+	"math/big"
+)
+
+var (
+	// Sadly this is missing from crypto/ecdsa compared to crypto/rsa
+	ErrECDSAVerification = errors.New("crypto/ecdsa: verification error")
+)
+
+// SigningMethodECDSA implements the ECDSA family of signing methods.
+// Expects *ecdsa.PrivateKey for signing and *ecdsa.PublicKey for verification
+type SigningMethodECDSA struct {
+	Name      string
+	Hash      crypto.Hash
+	KeySize   int
+	CurveBits int
+}
+
+// Specific instances for EC256 and company
+var (
+	SigningMethodES256 *SigningMethodECDSA
+	SigningMethodES384 *SigningMethodECDSA
+	SigningMethodES512 *SigningMethodECDSA
+)
+
+func init() {
+	// ES256
+	SigningMethodES256 = &SigningMethodECDSA{"ES256", crypto.SHA256, 32, 256}
+	RegisterSigningMethod(SigningMethodES256.Alg(), func() SigningMethod {
+		return SigningMethodES256
+	})
+
+	// ES384
+	SigningMethodES384 = &SigningMethodECDSA{"ES384", crypto.SHA384, 48, 384}
+	RegisterSigningMethod(SigningMethodES384.Alg(), func() SigningMethod {
+		return SigningMethodES384
+	})
+
+	// ES512
+	SigningMethodES512 = &SigningMethodECDSA{"ES512", crypto.SHA512, 66, 521}
+	RegisterSigningMethod(SigningMethodES512.Alg(), func() SigningMethod {
+		return SigningMethodES512
+	})
+}
+
+func (m *SigningMethodECDSA) Alg() string {
+	return m.Name
+}
+
+// Verify implements token verification for the SigningMethod.
+// For this verify method, key must be an ecdsa.PublicKey struct
+func (m *SigningMethodECDSA) Verify(signingString string, sig []byte, key any) error {
+	// Get the key
+	var ecdsaKey *ecdsa.PublicKey
+	switch k := key.(type) {
+	case *ecdsa.PublicKey:
+		ecdsaKey = k
+	default:
+		return newError("ECDSA verify expects *ecdsa.PublicKey", ErrInvalidKeyType)
+	}
+
+	if len(sig) != 2*m.KeySize {
+		return ErrECDSAVerification
+	}
+
+	r := big.NewInt(0).SetBytes(sig[:m.KeySize])
+	s := big.NewInt(0).SetBytes(sig[m.KeySize:])
+
+	// Create hasher
+	if !m.Hash.Available() {
+		return ErrHashUnavailable
+	}
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Verify the signature
+	if verifystatus := ecdsa.Verify(ecdsaKey, hasher.Sum(nil), r, s); verifystatus {
+		return nil
+	}
+
+	return ErrECDSAVerification
+}
+
+// Sign implements token signing for the SigningMethod.
+// For this signing method, key must be an ecdsa.PrivateKey struct
+func (m *SigningMethodECDSA) Sign(signingString string, key any) ([]byte, error) {
+	// Get the key
+	var ecdsaKey *ecdsa.PrivateKey
+	switch k := key.(type) {
+	case *ecdsa.PrivateKey:
+		ecdsaKey = k
+	default:
+		return nil, newError("ECDSA sign expects *ecdsa.PrivateKey", ErrInvalidKeyType)
+	}
+
+	// Create the hasher
+	if !m.Hash.Available() {
+		return nil, ErrHashUnavailable
+	}
+
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Sign the string and return r, s
+	if r, s, err := ecdsa.Sign(rand.Reader, ecdsaKey, hasher.Sum(nil)); err == nil {
+		curveBits := ecdsaKey.Curve.Params().BitSize
+
+		if m.CurveBits != curveBits {
+			return nil, ErrInvalidKey
+		}
+
+		keyBytes := curveBits / 8
+		if curveBits%8 > 0 {
+			keyBytes += 1
+		}
+
+		// We serialize the outputs (r and s) into big-endian byte arrays
+		// padded with zeros on the left to make sure the sizes work out.
+		// Output must be 2*keyBytes long.
+		out := make([]byte, 2*keyBytes)
+		r.FillBytes(out[0:keyBytes]) // r is assigned to the first half of output.
+		s.FillBytes(out[keyBytes:])  // s is assigned to the second half of output.
+
+		return out, nil
+	} else {
+		return nil, err
+	}
+}