fix: restore CLAUDE_CODE_MAX_OUTPUT_TOKENS env var support

Re-add the env var that was removed during SDK upgrade. Needed for
controlling output token limits in SDK subprocesses.

.env.example

@@ -1,6 +1,9 @@
 # Shannon Environment Configuration
 # Copy this file to .env and fill in your credentials
 
+# Recommended output token configuration for larger tool outputs
+CLAUDE_CODE_MAX_OUTPUT_TOKENS=64000
+
 # =============================================================================
 # OPTION 1: Direct Anthropic (default, no router)
 # =============================================================================