fix: bump upload limit to 11MB, add .gitignore for build artifacts

.gitignore

@@ -30,3 +30,5 @@ expenseflow-*
 
 # Go
 vendor/
+.go/
+app

internal/handlers/expenses.go

@@ -61,7 +61,7 @@ func NewExpenseHandler(db *sql.DB) *ExpenseHandler {
 //  5. Render templates/receipt_form.html with pre-filled fields or error banner
 func (h *ExpenseHandler) UploadReceipt(w http.ResponseWriter, r *http.Request) {
 	// 1. Parse multipart form with 10 MB max memory.
-	if err := r.ParseMultipartForm(10 << 20); err != nil {
+	if err := r.ParseMultipartForm(11 << 20); err != nil {
 		log.Printf("ERROR [%s] handlers: UploadReceipt: parse form: %v",
 			time.Now().Format(time.RFC3339), err)
 		renderUploadError(w, "Failed to parse upload form.")

main.go

@@ -127,7 +127,7 @@ func main() {
 	// Request body size limit (10 MB) on all endpoints.
 	r.Use(func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			r.Body = http.MaxBytesReader(w, r.Body, 10<<20)
+			r.Body = http.MaxBytesReader(w, r.Body, 11<<20)
 			next.ServeHTTP(w, r)
 		})
 	})