feat(achievement): add rank-up notifications (#165)

RE'd putDisplayed_achievement from ZZ client DLL via Ghidra: the packet
sends opcode + 1 zero byte with no achievement ID, acting as a blanket
"I saw everything" signal.

Server changes:
- Track per-character last-displayed levels in new displayed_levels
  column (migration 0008)
- GetAchievement compares current vs displayed levels per entry
- DisplayedAchievement snapshots current levels to clear notifications
- Repo, service, mock, and 3 new service tests

Protbot changes:
- New --action achievement: fetches achievements, shows rank-up markers,
  sends DISPLAYED_ACHIEVEMENT, re-fetches to verify notifications clear
- Packet builders for GET/ADD/DISPLAYED_ACHIEVEMENT

cmd/protbot/main.go

@@ -15,6 +15,7 @@ import (
 	"os"
 	"os/signal"
 	"syscall"
+	"time"
 
 	"erupe-ce/cmd/protbot/scenario"
 )
@@ -23,7 +24,7 @@ func main() {
 	signAddr := flag.String("sign-addr", "127.0.0.1:53312", "Sign server address (host:port)")
 	user := flag.String("user", "", "Username")
 	pass := flag.String("pass", "", "Password")
-	action := flag.String("action", "login", "Action to perform: login, lobby, session, chat, quests")
+	action := flag.String("action", "login", "Action to perform: login, lobby, session, chat, quests, achievement")
 	message := flag.String("message", "", "Chat message to send (used with --action chat)")
 	flag.Parse()
 
@@ -139,8 +140,78 @@ func main() {
 		fmt.Printf("[quests] Received %d bytes of quest data\n", len(data))
 		_ = scenario.Logout(result.Channel)
 
+	case "achievement":
+		result, err := scenario.Login(*signAddr, *user, *pass)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "login failed: %v\n", err)
+			os.Exit(1)
+		}
+		charID := result.Sign.CharIDs[0]
+		if _, err := scenario.SetupSession(result.Channel, charID); err != nil {
+			fmt.Fprintf(os.Stderr, "session setup failed: %v\n", err)
+			_ = result.Channel.Close()
+			os.Exit(1)
+		}
+		if err := scenario.EnterLobby(result.Channel); err != nil {
+			fmt.Fprintf(os.Stderr, "enter lobby failed: %v\n", err)
+			_ = result.Channel.Close()
+			os.Exit(1)
+		}
+
+		// Step 1: Get current achievements.
+		achs, err := scenario.GetAchievements(result.Channel, charID)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "get achievements failed: %v\n", err)
+			_ = scenario.Logout(result.Channel)
+			os.Exit(1)
+		}
+		fmt.Printf("[achievement] Total points: %d\n", achs.Points)
+		hasNotify := false
+		for _, e := range achs.Entries {
+			marker := ""
+			if e.Notify {
+				marker = " ** RANK UP **"
+				hasNotify = true
+			}
+			if e.Level > 0 || e.Notify {
+				fmt.Printf("  [%2d] Level %d  Progress %d/%d  Trophy 0x%02X%s\n",
+					e.ID, e.Level, e.Progress, e.Required, e.Trophy, marker)
+			}
+		}
+
+		// Step 2: Mark as displayed if there were notifications.
+		if hasNotify {
+			fmt.Println("[achievement] Sending DISPLAYED_ACHIEVEMENT to acknowledge rank-ups...")
+			if err := scenario.DisplayedAchievement(result.Channel); err != nil {
+				fmt.Fprintf(os.Stderr, "displayed achievement failed: %v\n", err)
+			}
+			// Brief pause for fire-and-forget packet to be processed.
+			<-time.After(500 * time.Millisecond)
+
+			// Step 3: Re-fetch to verify notifications are cleared.
+			achs2, err := scenario.GetAchievements(result.Channel, charID)
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "re-fetch achievements failed: %v\n", err)
+			} else {
+				cleared := true
+				for _, e := range achs2.Entries {
+					if e.Notify {
+						fmt.Printf("  [%2d] STILL notifying (level %d) — not cleared!\n", e.ID, e.Level)
+						cleared = false
+					}
+				}
+				if cleared {
+					fmt.Println("[achievement] All rank-up notifications cleared successfully.")
+				}
+			}
+		} else {
+			fmt.Println("[achievement] No pending rank-up notifications.")
+		}
+
+		_ = scenario.Logout(result.Channel)
+
 	default:
-		fmt.Fprintf(os.Stderr, "unknown action: %s (supported: login, lobby, session, chat, quests)\n", *action)
+		fmt.Fprintf(os.Stderr, "unknown action: %s (supported: login, lobby, session, chat, quests, achievement)\n", *action)
 		os.Exit(1)
 	}
 }