✅ split sync tests by behavior boundary

src/sync_facades_test.mbt

@@ -0,0 +1,17 @@
+///|
+// Sync facade tests were split by facade responsibility.
+// Add new facade checks to the focused files in this package instead of
+// growing this historical catch-all file again.
+//
+// Current layout:
+// - library_logger_facade_test.mbt
+// - library_logger_builder_test.mbt
+// - parsed_library_logger_test.mbt
+// - configured_logger_facade_test.mbt
+// - application_logger_facade_test.mbt
+// - parsed_application_logger_test.mbt
+// - sync_parse_build_facade_test.mbt
+// - BitLogger_test.mbt
+// - text_formatter_test.mbt
+// - file_sink_test.mbt
+// - sink_graph_surface_test.mbt