feat(api): add OAuth token fields and new provider types support

Add support for OAuth-based authentication with access/refresh tokens
and expiration tracking for API keys. Extend provider groups with
static headers configuration and headers profile options.

Changes include:
- Add AccessToken, RefreshToken, ExpiresAt, AccountID, ProjectID to APIKey model
- Add StaticHeaders and HeadersProfile to ProviderGroup model
- Add TokenRefresh configuration for background token management
- Support new provider types: ClaudeCode, Codex, GeminiCLI, Antigravity
- Update sync service to include new fields in provider snapshots

internal/service/sync.go

@@ -278,8 +278,14 @@ type providerSnapshot struct {
 	Type           string   `json:"type"`
 	BaseURL        string   `json:"base_url"`
 	APIKey         string   `json:"api_key"`
+	AccessToken    string   `json:"access_token,omitempty"`
+	ExpiresAt      int64    `json:"expires_at,omitempty"`
+	AccountID      string   `json:"account_id,omitempty"`
+	ProjectID      string   `json:"project_id,omitempty"`
 	GoogleProject  string   `json:"google_project,omitempty"`
 	GoogleLocation string   `json:"google_location,omitempty"`
+	StaticHeaders  string   `json:"static_headers,omitempty"`
+	HeadersProfile string   `json:"headers_profile,omitempty"`
 	GroupID        uint     `json:"group_id,omitempty"`
 	Group          string   `json:"group"`
 	Models         []string `json:"models"`
@@ -333,8 +339,13 @@ func (s *SyncService) writeProvidersSnapshot(ctx context.Context, pipe redis.Pip
 			Type:           strings.TrimSpace(g.Type),
 			BaseURL:        strings.TrimSpace(g.BaseURL),
 			APIKey:         strings.TrimSpace(k.APIKey),
+			AccessToken:    strings.TrimSpace(k.AccessToken),
 			GoogleProject:  strings.TrimSpace(g.GoogleProject),
 			GoogleLocation: strings.TrimSpace(g.GoogleLocation),
+			StaticHeaders:  strings.TrimSpace(g.StaticHeaders),
+			HeadersProfile: strings.TrimSpace(g.HeadersProfile),
+			AccountID:      strings.TrimSpace(k.AccountID),
+			ProjectID:      strings.TrimSpace(k.ProjectID),
 			GroupID:        g.ID,
 			Group:          groupName,
 			Models:         models,
@@ -343,6 +354,9 @@ func (s *SyncService) writeProvidersSnapshot(ctx context.Context, pipe redis.Pip
 			AutoBan:        k.AutoBan,
 			BanReason:      strings.TrimSpace(k.BanReason),
 		}
+		if k.ExpiresAt != nil {
+			snap.ExpiresAt = k.ExpiresAt.UTC().Unix()
+		}
 		if k.BanUntil != nil {
 			snap.BanUntil = k.BanUntil.UTC().Unix()
 		}