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/ex08-map-race/main.go

@@ -0,0 +1,22 @@
+// PREDICT: what happens? Can recover() save you? Run it a few times.
+// Then run with: go run -race .
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func main() {
+	defer func() {
+		if r := recover(); r != nil {
+			fmt.Println("recovered:", r) // will this ever print?
+		}
+	}()
+	m := make(map[int]int)
+	for i := 0; i < 100; i++ {
+		go func(i int) { m[i] = i }(i)
+	}
+	time.Sleep(200 * time.Millisecond)
+	fmt.Println(len(m))
+}