fix(api): bump go toolchain for security audit

Raise the API module to go1.26.2 so setup-go stops selecting a vulnerable standard library release, and add a regression test that fails on affected 1.26.x toolchains.

Closes #14

apps/api/go.mod

@@ -1,6 +1,6 @@
 module github.com/xdrop/monorepo
 
-go 1.26.1
+go 1.26.2
 
 require (
 	github.com/aws/aws-sdk-go-v2 v1.41.5