fix: keep packages/altimate-engine/** in keepOurs for backward-compat

upstream-merge-guard.test.ts requires this entry in the critical
keepOurs list. The Python engine was eliminated in commit 845ee98,
but the glob entry harmlessly matches nothing today and covers the
directory if anyone re-adds it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: anandgupta42

script/upstream/utils/config.ts

@@ -258,8 +258,11 @@ export const defaultConfig: MergeConfig = {
     "github/README.md",
     "github/index.ts",
     "install",
-    // Note: packages/altimate-engine/** was removed when the Python engine was
-    // eliminated (commit 845ee98271). Kept entry intentionally absent.
+    // packages/altimate-engine/** — kept for backwards compatibility with the
+    // upstream-merge-guard regression test even though the Python engine was
+    // eliminated in commit 845ee98271. Glob matches nothing today; it'll cover
+    // the directory if anyone re-adds it.
+    "packages/altimate-engine/**",
     "packages/drivers/**",
     "packages/opencode/src/altimate/**",
     "packages/opencode/src/bridge/**",