fix(agents): make image sanitization dimension configurable

src/config/types.agent-defaults.ts

@@ -190,6 +190,11 @@ export type AgentDefaultsConfig = {
   timeoutSeconds?: number;
   /** Max inbound media size in MB for agent-visible attachments (text note or future image attach). */
   mediaMaxMb?: number;
+  /**
+   * Max image side length (pixels) when sanitizing base64 image payloads in transcripts/tool results.
+   * Default: 1200.
+   */
+  imageMaxDimensionPx?: number;
   typingIntervalSeconds?: number;
   /** Typing indicator start mode (never|instant|thinking|message). */
   typingMode?: TypingMode;