merge: origin/main v1.1.1.0 into garrytan/fix-checkpoints

Main shipped the /ship VERSION/package.json drift-detection fix as
v1.1.1.0 — exact collision with our branch's existing version. Bumped
ours to 1.1.2.0.

Resolved conflicts:
- VERSION: 1.1.1.0 → 1.1.2.0
- package.json: 1.1.1.0 → 1.1.2.0
- CHANGELOG.md: moved our /checkpoint → /context-save entry up one
  header level to [1.1.2.0] and kept main's /ship drift-fix entry
  at [1.1.1.0]. Sequence now: 1.1.2.0 → 1.1.1.0 → 1.1.0.0 → 1.0.0.0.
- Migration renamed v1.1.1.0.sh → v1.1.2.0.sh (version string inside
  and test path reference both updated).

Also bumped the /context-save + /context-restore CHANGELOG entry to
credit the adversarial-review hardening wave (HOME guard, realpath
fallback, title sanitize, collision-safe filenames, context-restore
head cap, autoplan test regex tightening) as contributor-facing notes
— previous entry didn't reflect the security work that landed after
the initial ship.

No overlap between main's /ship Step 12 logic and this branch's work.
SKILL.md files regenerated via bun run gen:skill-docs --host all.
Golden fixtures updated.

bun test: 0 failures across 80+ targeted tests and the full suite.
Migration ownership guard: 7/7 pass (~85ms).

package.json

@@ -1,6 +1,6 @@
 {
   "name": "gstack",
-  "version": "1.1.1.0",
+  "version": "1.1.2.0",
   "description": "Garry's Stack — Claude Code skills + fast headless browser. One repo, one install, entire AI engineering workflow.",
   "license": "MIT",
   "type": "module",