chore: register registry_mcp in .mcp.json

Auto-loads registry MCP server (fn_search, fn_show, fn_code,
fn_list_domains, fn_uses, fn_doctor, fn_run, fn_create_function)
in any Claude Code session opened from this repo.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.mcp.json

@@ -0,0 +1,11 @@
+{
+  "mcpServers": {
+    "registry": {
+      "command": "/home/lucas/fn_registry/apps/registry_mcp/registry_mcp",
+      "args": ["--enable-run", "--enable-write"],
+      "env": {
+        "FN_REGISTRY_ROOT": "/home/lucas/fn_registry"
+      }
+    }
+  }
+}