v1.91.254.0 pregate: starter policy, benign-finding allowlist, environment vs diff failures, per-run scratch

Merge origin/main (4d48d39e51, v1.91.253.0) and restamp at slot 1.

FILES: CHANGELOG.md VERSION agents-digest/gstack-AGENTS.md package.json
MERGE_CONDITION: sha=c3c96b3ad0af6a486958872020ace795e83a8f2d
NEW_VERSION=1.91.254.0

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "gstack",
-  "version": "1.91.248",
+  "version": "1.91.254",
   "description": "Garry's Stack — Claude Code skills + fast headless browser. One repo, one install, entire AI engineering workflow.",
   "license": "MIT",
   "type": "module",