fix(stack-service): normalize commit stats shape

Convert various backend commit stats shapes into a single frontend
format expected by the UI. Some responses use camelCase keys
(linesAdded/linesRemoved/filesChanged) while others use snake_case
(lines_added/lines_removed/files_changed). The code now detects the
shape and maps snake_case to the canonical camelCase shape before
storing in the response transform.

This prevents mismatched stat access and makes downstream code rely on
one consistent stats object.

Author: PavelLaptev

apps/desktop/src/lib/stacks/stackService.svelte.ts

@@ -1175,10 +1175,25 @@ function injectEndpoints(api: ClientState['backendApi'], uiState: UiState) {
 				],
 				transformResponse(rsp: CommitDetails) {
 					const changes = changesAdapter.addMany(changesAdapter.getInitialState(), rsp.changes);
+					const rawStats = rsp.stats as
+						| TreeStats
+						| {
+								lines_added: number;
+								lines_removed: number;
+								files_changed: number;
+						  };
+					const stats =
+						'linesAdded' in rawStats
+							? rawStats
+							: {
+									linesAdded: rawStats.lines_added,
+									linesRemoved: rawStats.lines_removed,
+									filesChanged: rawStats.files_changed
+								};
 					return {
 						changes: changes,
 						details: rsp.commit,
-						stats: rsp.stats,
+						stats,
 						conflictEntries: rsp.conflictEntries
 							? new ConflictEntries(
 									rsp.conflictEntries.ancestorEntries,