Initial commit: Go SRE interview exercises

Includes solved 02-worker-pool and 09-safe-counter (mutex, atomic, sharded).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GbnJj9ZqEx9nUvzkjdwfMq

10-gotchas/ex02-deadlock/main.go

@@ -0,0 +1,10 @@
+// PREDICT: what happens? Then run it. Then fix it TWO different ways.
+package main
+
+import "fmt"
+
+func main() {
+	ch := make(chan int)
+	ch <- 1
+	fmt.Println(<-ch)
+}