Add Go file structure conventions to AGENTS.md

AGENTS.md

@@ -5,3 +5,14 @@
 At the start of every conversation, load the following skills using the `skill` tool before responding to the user:
 
 1. **caveman** — Always use caveman mode (full intensity) for all responses
+
+## Code Organization
+
+### Go file structure
+- Public (exported) functions must appear at the top of each file.
+- Private (unexported) functions must appear at the bottom of each file.
+- Within each section, functions must be sorted alphabetically by function name.
+- The two sections must be separated by exactly this divider:
+
+	// -----------------------------------------
+	// private