feat: Configure Modal API credentials

- Added Modal API token configuration
- Token ID: ak-hF71TECrOEALA208DHoUHp
- Token Secret: as-364JrJ2yd0y3tN3cw7z6Uh
- Integration ready, testing auth format
- Will work once correct token format is determined

agents/cast-iron-scout/modal_config.json

@@ -0,0 +1,6 @@
+{
+  "token_id": "ak-hF71TECrOEALA208DHoUHp",
+  "token_secret": "as-364JrJ2yd0y3tN3cw7z6Uh",
+  "model": "zai-org/GLM-5.1-FP8",
+  "endpoint": "https://api.us-west-2.modal.direct/v1/chat/completions"
+}