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/google/uuid/null.go

@@ -0,0 +1,118 @@
+// Copyright 2021 Google Inc.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package uuid
+
+import (
+	"bytes"
+	"database/sql/driver"
+	"encoding/json"
+	"fmt"
+)
+
+var jsonNull = []byte("null")
+
+// NullUUID represents a UUID that may be null.
+// NullUUID implements the SQL driver.Scanner interface so
+// it can be used as a scan destination:
+//
+//  var u uuid.NullUUID
+//  err := db.QueryRow("SELECT name FROM foo WHERE id=?", id).Scan(&u)
+//  ...
+//  if u.Valid {
+//     // use u.UUID
+//  } else {
+//     // NULL value
+//  }
+//
+type NullUUID struct {
+	UUID  UUID
+	Valid bool // Valid is true if UUID is not NULL
+}
+
+// Scan implements the SQL driver.Scanner interface.
+func (nu *NullUUID) Scan(value interface{}) error {
+	if value == nil {
+		nu.UUID, nu.Valid = Nil, false
+		return nil
+	}
+
+	err := nu.UUID.Scan(value)
+	if err != nil {
+		nu.Valid = false
+		return err
+	}
+
+	nu.Valid = true
+	return nil
+}
+
+// Value implements the driver Valuer interface.
+func (nu NullUUID) Value() (driver.Value, error) {
+	if !nu.Valid {
+		return nil, nil
+	}
+	// Delegate to UUID Value function
+	return nu.UUID.Value()
+}
+
+// MarshalBinary implements encoding.BinaryMarshaler.
+func (nu NullUUID) MarshalBinary() ([]byte, error) {
+	if nu.Valid {
+		return nu.UUID[:], nil
+	}
+
+	return []byte(nil), nil
+}
+
+// UnmarshalBinary implements encoding.BinaryUnmarshaler.
+func (nu *NullUUID) UnmarshalBinary(data []byte) error {
+	if len(data) != 16 {
+		return fmt.Errorf("invalid UUID (got %d bytes)", len(data))
+	}
+	copy(nu.UUID[:], data)
+	nu.Valid = true
+	return nil
+}
+
+// MarshalText implements encoding.TextMarshaler.
+func (nu NullUUID) MarshalText() ([]byte, error) {
+	if nu.Valid {
+		return nu.UUID.MarshalText()
+	}
+
+	return jsonNull, nil
+}
+
+// UnmarshalText implements encoding.TextUnmarshaler.
+func (nu *NullUUID) UnmarshalText(data []byte) error {
+	id, err := ParseBytes(data)
+	if err != nil {
+		nu.Valid = false
+		return err
+	}
+	nu.UUID = id
+	nu.Valid = true
+	return nil
+}
+
+// MarshalJSON implements json.Marshaler.
+func (nu NullUUID) MarshalJSON() ([]byte, error) {
+	if nu.Valid {
+		return json.Marshal(nu.UUID)
+	}
+
+	return jsonNull, nil
+}
+
+// UnmarshalJSON implements json.Unmarshaler.
+func (nu *NullUUID) UnmarshalJSON(data []byte) error {
+	if bytes.Equal(data, jsonNull) {
+		*nu = NullUUID{}
+		return nil // valid null UUID
+	}
+	err := json.Unmarshal(data, &nu.UUID)
+	nu.Valid = err == nil
+	return err
+}