docs: v0.9.8.0 — deploy pipeline + E2E performance + pre-merge gate

CHANGELOG: added v0.9.8.0 entry covering /land-and-deploy, /canary,
/benchmark, /setup-deploy, /review perf pass, E2E model pinning,
and 3 test fixes.

README: added 4 new skills to tables and install instructions,
updated specialist/tool counts (18+7), added deploy pipeline to
"What's new" section.

/land-and-deploy: added Step 3.5 pre-merge readiness gate that
checks review dashboard, E2E results, free tests, and doc-release
status before merging. Uses AskUserQuestion for explicit confirmation.

VERSION: 0.9.7.0 → 0.9.8.0
TODOS: updated deploy pipeline to Completed.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "gstack",
-  "version": "0.3.3",
+  "version": "0.9.8.0",
   "description": "Garry's Stack — Claude Code skills + fast headless browser. One repo, one install, entire AI engineering workflow.",
   "license": "MIT",
   "type": "module",