chore(client): track Godot .uid resource identifier files

These are auto-generated by Godot 4 to provide stable resource
references across renames. Tracking them prevents UID divergence.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/scripts/autoloads/ui_strings.gd.uid

@@ -0,0 +1 @@
+uid://xm2hswjm3pss

client/tests/test_input_roundtrip.gd.uid

@@ -0,0 +1 @@
+uid://st3laseti33k

client/tests/test_ui_strings.gd.uid

@@ -0,0 +1 @@
+uid://c6vjj0dwiy80i