Fix Go cookbook recipes to use correct SDK API

All 5 Go recipes and their markdown docs used incorrect API patterns
that don't match the real github.com/github/copilot-sdk/go v0.1.23:

- copilot.NewClient() -> copilot.NewClient(nil) (*ClientOptions param)
- client.Start() -> client.Start(ctx) (context.Context required)
- copilot.SessionConfig -> &copilot.SessionConfig (pointer required)
- session.On(func(event copilot.Event)) -> session.On(func(event copilot.SessionEvent))
- Type assertions -> event.Type string check + *event.Data.Content deref
- session.WaitForIdle() -> session.SendAndWait(ctx, ...) (WaitForIdle doesn't exist)
- copilot.SystemMessage -> copilot.SystemMessageConfig

All 5 recipes verified to compile against SDK v0.1.23.

cookbook/copilot-sdk/go/recipe/persisting-sessions.go

@@ -1,68 +1,68 @@
 package main
 
 import (
-    "fmt"
-    "log"
+	"context"
+	"fmt"
+	"log"
 
-    "github.com/github/copilot-sdk/go"
+	copilot "github.com/github/copilot-sdk/go"
 )
 
 func main() {
-    client := copilot.NewClient()
-    if err := client.Start(); err != nil {
-        log.Fatal(err)
-    }
-    defer client.Stop()
+	ctx := context.Background()
+	client := copilot.NewClient(nil)
+	if err := client.Start(ctx); err != nil {
+		log.Fatal(err)
+	}
+	defer client.Stop()
 
-    // Create session with a memorable ID
-    session, err := client.CreateSession(copilot.SessionConfig{
-        SessionID: "user-123-conversation",
-        Model:     "gpt-5",
-    })
-    if err != nil {
-        log.Fatal(err)
-    }
+	// Create session with a memorable ID
+	session, err := client.CreateSession(ctx, &copilot.SessionConfig{
+		SessionID: "user-123-conversation",
+		Model:     "gpt-5",
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
 
-    if err := session.Send(copilot.MessageOptions{Prompt: "Let's discuss TypeScript generics"}); err != nil {
-        log.Fatal(err)
-    }
-    fmt.Printf("Session created: %s\n", session.SessionID)
+	_, err = session.SendAndWait(ctx, copilot.MessageOptions{Prompt: "Let's discuss TypeScript generics"})
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("Session created: %s\n", session.SessionID)
 
-    // Destroy session but keep data on disk
-    if err := session.Destroy(); err != nil {
-        log.Fatal(err)
-    }
-    fmt.Println("Session destroyed (state persisted)")
+	// Destroy session but keep data on disk
+	session.Destroy()
+	fmt.Println("Session destroyed (state persisted)")
 
-    // Resume the previous session
-    resumed, err := client.ResumeSession("user-123-conversation")
-    if err != nil {
-        log.Fatal(err)
-    }
-    fmt.Printf("Resumed: %s\n", resumed.SessionID)
+	// Resume the previous session
+	resumed, err := client.ResumeSession(ctx, "user-123-conversation")
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("Resumed: %s\n", resumed.SessionID)
 
-    if err := resumed.Send(copilot.MessageOptions{Prompt: "What were we discussing?"}); err != nil {
-        log.Fatal(err)
-    }
+	_, err = resumed.SendAndWait(ctx, copilot.MessageOptions{Prompt: "What were we discussing?"})
+	if err != nil {
+		log.Fatal(err)
+	}
 
-    // List sessions
-    sessions, err := client.ListSessions()
-    if err != nil {
-        log.Fatal(err)
-    }
-    ids := make([]string, 0, len(sessions))
-    for _, s := range sessions {
-        ids = append(ids, s.SessionID)
-    }
-    fmt.Printf("Sessions: %v\n", ids)
+	// List sessions
+	sessions, err := client.ListSessions(ctx)
+	if err != nil {
+		log.Fatal(err)
+	}
+	ids := make([]string, 0, len(sessions))
+	for _, s := range sessions {
+		ids = append(ids, s.SessionID)
+	}
+	fmt.Printf("Sessions: %v\n", ids)
 
-    // Delete session permanently
-    if err := client.DeleteSession("user-123-conversation"); err != nil {
-        log.Fatal(err)
-    }
-    fmt.Println("Session deleted")
+	// Delete session permanently
+	if err := client.DeleteSession(ctx, "user-123-conversation"); err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println("Session deleted")
 
-    if err := resumed.Destroy(); err != nil {
-        log.Fatal(err)
-    }
+	resumed.Destroy()
 }