feat(installer): prefer npm next lane (#688)

--next now prefers a fast npm @next install (CLI + gateway from the Gitea registry) and falls back to source build at next if the dist-tag is unavailable. Registry lane gated to non-dev, non-explicit-ref next installs; CLI/gateway prerelease versions must share a pipeline suffix. Adds tools/install-next-lane.test.sh (wired into CI). PR-event CI 1635 fully green + review-of-record APPROVE (functional install test, head 2fd7cfc3).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

package.json

@@ -7,7 +7,8 @@
     "dev": "turbo run dev",
     "lint": "turbo run lint",
     "typecheck": "turbo run typecheck",
-    "test": "turbo run test",
+    "test": "turbo run test && pnpm run test:installer",
+    "test:installer": "bash tools/install-next-lane.test.sh",
     "format": "prettier --write \"**/*.{ts,tsx,js,jsx,json,md}\"",
     "format:check": "prettier --check \"**/*.{ts,tsx,js,jsx,json,md}\"",
     "prepare": "husky"