feat(enterprise-site): add PbootCMS enterprise site publisher

Introduce a new enterprise-site publishing channel that lets tenants push
articles to self-hosted PbootCMS sites alongside the existing media supply
flow.

Backend (server/internal/tenant):
- enterprise_site_service: CRUD, ping, category sync, and article publish
- enterprise_site_pbootcms: PbootCMS API client integration
- enterprise_site_crypto: encrypt/decrypt stored site credentials
- enterprise_site_handler + routes under /enterprise-sites
- migrations for the enterprise site publisher tables
- config: add SERVER_PUBLIC_BASE_URL (Server.PublicBaseURL) for callbacks
- article/media services adjusted to support the publish flow

Frontend (apps/admin-web):
- PublishArticleModal & ArticlePublishStatus: enterprise-site publish UI
- MediaView: manage enterprise sites and categories
- api + shared-types: enterprise site endpoints and types
- http-client: add PATCH method support

Integrations:
- pbootcms GeoPublisher controller plugin + install guide
- docs/enterprise-site-publisher-v1.md design doc

server/internal/tenant/app/enterprise_site_crypto.go

@@ -0,0 +1,78 @@
+package app
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"fmt"
+	"io"
+	"strings"
+)
+
+const enterpriseSiteCredentialPrefix = "v1:"
+
+func encryptEnterpriseSiteCredential(secret string, keyMaterial string) (string, error) {
+	secret = strings.TrimSpace(secret)
+	if secret == "" {
+		return "", fmt.Errorf("enterprise site credential is empty")
+	}
+	key := enterpriseSiteCredentialKey(keyMaterial)
+	block, err := aes.NewCipher(key[:])
+	if err != nil {
+		return "", fmt.Errorf("create enterprise site credential cipher: %w", err)
+	}
+	aead, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", fmt.Errorf("create enterprise site credential gcm: %w", err)
+	}
+	nonce := make([]byte, aead.NonceSize())
+	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
+		return "", fmt.Errorf("generate enterprise site credential nonce: %w", err)
+	}
+	ciphertext := aead.Seal(nil, nonce, []byte(secret), nil)
+	packed := append(nonce, ciphertext...)
+	return enterpriseSiteCredentialPrefix + base64.StdEncoding.EncodeToString(packed), nil
+}
+
+func decryptEnterpriseSiteCredential(ciphertext string, keyMaterial string) (string, error) {
+	ciphertext = strings.TrimSpace(ciphertext)
+	if ciphertext == "" {
+		return "", fmt.Errorf("enterprise site credential ciphertext is empty")
+	}
+	if !strings.HasPrefix(ciphertext, enterpriseSiteCredentialPrefix) {
+		return "", fmt.Errorf("unsupported enterprise site credential format")
+	}
+	raw, err := base64.StdEncoding.DecodeString(strings.TrimPrefix(ciphertext, enterpriseSiteCredentialPrefix))
+	if err != nil {
+		return "", fmt.Errorf("decode enterprise site credential: %w", err)
+	}
+	key := enterpriseSiteCredentialKey(keyMaterial)
+	block, err := aes.NewCipher(key[:])
+	if err != nil {
+		return "", fmt.Errorf("create enterprise site credential cipher: %w", err)
+	}
+	aead, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", fmt.Errorf("create enterprise site credential gcm: %w", err)
+	}
+	if len(raw) <= aead.NonceSize() {
+		return "", fmt.Errorf("enterprise site credential payload is invalid")
+	}
+	nonce := raw[:aead.NonceSize()]
+	encrypted := raw[aead.NonceSize():]
+	plaintext, err := aead.Open(nil, nonce, encrypted, nil)
+	if err != nil {
+		return "", fmt.Errorf("decrypt enterprise site credential: %w", err)
+	}
+	return string(plaintext), nil
+}
+
+func enterpriseSiteCredentialKey(keyMaterial string) [32]byte {
+	trimmed := strings.TrimSpace(keyMaterial)
+	if trimmed == "" {
+		trimmed = "geo-rankly-enterprise-site-development-key"
+	}
+	return sha256.Sum256([]byte("enterprise-site-credential:" + trimmed))
+}