Update auth references from JWT to session tokens

- Remove previous_token_grace_until from RotateApiTokenResponse
- Update setToken JSDoc and CLI help text
- Update README auth documentation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/client.ts

@@ -66,7 +66,7 @@ export class ElydoraClient {
   }
 
   /**
-   * Set the JWT token used for authenticated API calls.
+   * Set the API token used for authenticated API calls.
    */
   setToken(token: string): void {
     this.token = token;