Add 7 missing SDK methods and fix README type name

- Fix AgentKeyRequest → RegisterAgentKeyInput in README
- Add ListAgents, UnfreezeAgent, DeleteAgent to agents.go
- Add GetMe, IssueApiToken to auth.go
- Add DownloadExport to exports.go
- Add Health package-level function in health.go
- Add corresponding types and document all exports in README

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

exports.go

@@ -1,6 +1,11 @@
 package elydora
 
-import "fmt"
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+)
 
 // CreateExport creates a new compliance export job.
 func (c *Client) CreateExport(params *CreateExportRequest) (*CreateExportResponse, error) {
@@ -28,3 +33,47 @@ func (c *Client) GetExport(exportID string) (*GetExportResponse, error) {
 	}
 	return &result, nil
 }
+
+// DownloadExport downloads the raw file data for a completed export.
+func (c *Client) DownloadExport(exportID string) ([]byte, error) {
+	u := c.baseURL + fmt.Sprintf("/v1/exports/%s/download", exportID)
+
+	req, err := http.NewRequest(http.MethodGet, u, nil)
+	if err != nil {
+		return nil, fmt.Errorf("elydora: create request: %w", err)
+	}
+	if c.token != "" {
+		req.Header.Set("Authorization", "Bearer "+c.token)
+	}
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("elydora: http request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("elydora: read response body: %w", err)
+	}
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		var errResp errorResponse
+		if jsonErr := json.Unmarshal(body, &errResp); jsonErr == nil && errResp.Error.Code != "" {
+			return nil, &ElydoraError{
+				StatusCode: resp.StatusCode,
+				Code:       errResp.Error.Code,
+				Message:    errResp.Error.Message,
+				RequestID:  errResp.Error.RequestID,
+				Details:    errResp.Error.Details,
+			}
+		}
+		return nil, &ElydoraError{
+			StatusCode: resp.StatusCode,
+			Code:       ErrorCodeInternalError,
+			Message:    string(body),
+		}
+	}
+
+	return body, nil
+}