feat(02-02): convert handlers to Server struct methods, remove globals

- Add Server struct with store Store and webhookSecret fields
- Add NewServer constructor
- Convert all 6 handler functions to methods on *Server
- Replace all inline SQL with s.store.X() calls
- Remove package-level globals db, mu, webhookSecret
- Remove InitDB, SetWebhookSecret, UpdateEvent, GetUpdates functions
- Update export_test.go: replace old helpers with NewTestServer, NewTestServerWithSecret, TestUpsertEvent, TestGetUpdatesMap
- Update main.go: sql.Open -> RunMigrations -> NewSQLiteStore -> NewServer -> routes

cmd/diunwebhook/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"database/sql"
 	"errors"
 	"log"
 	"net/http"
@@ -11,6 +12,7 @@ import (
 	"time"
 
 	diun "awesomeProject/pkg/diunwebhook"
+	_ "modernc.org/sqlite"
 )
 
 func main() {
@@ -18,33 +20,42 @@ func main() {
 	if dbPath == "" {
 		dbPath = "./diun.db"
 	}
-	if err := diun.InitDB(dbPath); err != nil {
-		log.Fatalf("InitDB: %v", err)
+
+	db, err := sql.Open("sqlite", dbPath)
+	if err != nil {
+		log.Fatalf("sql.Open: %v", err)
 	}
 
+	if err := diun.RunMigrations(db); err != nil {
+		log.Fatalf("RunMigrations: %v", err)
+	}
+
+	store := diun.NewSQLiteStore(db)
+
 	secret := os.Getenv("WEBHOOK_SECRET")
 	if secret == "" {
 		log.Println("WARNING: WEBHOOK_SECRET not set — webhook endpoint is unprotected")
 	} else {
-		diun.SetWebhookSecret(secret)
 		log.Println("Webhook endpoint protected with token authentication")
 	}
 
+	srv := diun.NewServer(store, secret)
+
 	port := os.Getenv("PORT")
 	if port == "" {
 		port = "8080"
 	}
 
 	mux := http.NewServeMux()
-	mux.HandleFunc("/webhook", diun.WebhookHandler)
-	mux.HandleFunc("/api/updates/", diun.DismissHandler)
-	mux.HandleFunc("/api/updates", diun.UpdatesHandler)
-	mux.HandleFunc("/api/tags", diun.TagsHandler)
-	mux.HandleFunc("/api/tags/", diun.TagByIDHandler)
-	mux.HandleFunc("/api/tag-assignments", diun.TagAssignmentHandler)
+	mux.HandleFunc("/webhook", srv.WebhookHandler)
+	mux.HandleFunc("/api/updates/", srv.DismissHandler)
+	mux.HandleFunc("/api/updates", srv.UpdatesHandler)
+	mux.HandleFunc("/api/tags", srv.TagsHandler)
+	mux.HandleFunc("/api/tags/", srv.TagByIDHandler)
+	mux.HandleFunc("/api/tag-assignments", srv.TagAssignmentHandler)
 	mux.Handle("/", http.FileServer(http.Dir("./frontend/dist")))
 
-	srv := &http.Server{
+	httpSrv := &http.Server{
 		Addr:         ":" + port,
 		Handler:      mux,
 		ReadTimeout:  10 * time.Second,
@@ -57,7 +68,7 @@ func main() {
 
 	go func() {
 		log.Printf("Listening on :%s", port)
-		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
+		if err := httpSrv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
 			log.Fatalf("ListenAndServe: %v", err)
 		}
 	}()
@@ -67,7 +78,7 @@ func main() {
 	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
 	defer cancel()
 
-	if err := srv.Shutdown(ctx); err != nil {
+	if err := httpSrv.Shutdown(ctx); err != nil {
 		log.Printf("Shutdown error: %v", err)
 	} else {
 		log.Println("Server stopped cleanly")