backend barebone done, big chunk of work done

server/internal/store/errors.go

@@ -0,0 +1,11 @@
+package store
+
+import (
+	"errors"
+)
+
+// ErrNotFound is returned when a record is not found in the store.
+var ErrNotFound = errors.New("store: not found")
+
+// ErrDuplicate is returned when attempting to create a record that already exists.
+var ErrDuplicate = errors.New("store: duplicate")