feat(explorer): stage and remove-from-staging selected item (#4546)

[natechadwick-intsof]

Summary

Content Explorer slice 2 of parent #4530: an Editor/Admin can Stage and Remove from Staging a selected page or asset from the React Explorer toolbar/context menu.

Follows the Publish Now / Take Down peer (itemPublish.ts + actionDispatch.ts): confirm, resolvePublishKind (folders/templates stay unavailable), injected Finder actions (CX catalogs omit them), classic sitemanage GETs (/publish/page|resource/staging/{id} and /takedown/page|resource/staging/{id}), and mapPublishResponse so HTTP 200 FORBIDDEN / BADCONFIG / NOSTAGING_SERVERS is an error, not success.

Out of scope: schedule dates (#4547/#4535), Take Down (already #4533/#4545), PublishingShell history (#4536–#4538 / PR #4549). Duplicate filing #4534 is not a second PR.

Operator: Grok: night-issue-prs (model grok-4.6)

Fixes #4546
Parent: #4530

Test plan

1. QA H2: python docker/scripts/perc-devctl.py qa-up then qa-health with QA_CMS_HOST_PORT from qa-up stdout (this run: http://127.0.0.1:9993).
2. Hot-deploy WebUI: python docker/scripts/perc-devctl.py qa-deploy-webui; qa-health again.
3. Select a page or asset in Explorer (spa.jsp?entry=explorer). Confirm Stage / Remove from Staging appear; they stay hidden on Sites/folders.
4. Playwright: npm run test:surface -- --path tests/explorer-action-dispatch.spec.js (FORBIDDEN / NOSTAGING intercepts) and npm run test:golden.
5. Confirm HTTP 200 FORBIDDEN / NOSTAGING_SERVERS shows Server actions error and does not refresh as success.

Checklist

• Product documentation — updated product-docs/8.2/admin/content-explorer.md (Stage / Remove from Staging rows)
• Unit / module tests — Vitest for itemPublish / dispatch / enablement / shell; standalone mvnw clean install on WebUI and modules/perc-qa-automation
• WebUI + Playwright — explorer-action-dispatch.spec.js @explorer-staging + golden smoke
• Build gates — standalone clean install; C2 N/A (no Java final/API shape change)
• Cross-platform — N/A (REST URL paths only; no filesystem I/O)

C3 evidence

• modules_built: WebUI, modules/perc-qa-automation
• build_evidence:
  • cd WebUI && JAVA_HOME=/usr/lib/jvm/java-21-openjdk ../mvnw clean install → BUILD SUCCESS (Surefire Tests run: 69, Failures: 0; Vitest Test Files 443 passed, Tests 4289 passed)
  • cd modules/perc-qa-automation && JAVA_HOME=/usr/lib/jvm/java-21-openjdk ../../mvnw clean install → BUILD SUCCESS (npm ci; no Java tests)
• downstream_checked: none (C2 did not apply — no final/public Java API change)

C5 UI proof

• qa-up: python docker/scripts/perc-devctl.py qa-up → TEST_CMS_URL=http://127.0.0.1:9993 QA_CONTAINER=perc-matrix-cms-h2
• qa-health (explicit published URL; env-resolved freeport was stale): RESULT:OK STEP:qa-health HTTP:200 HEALTH:healthy URL:http://127.0.0.1:9993/Rhythmyx/rest/mimetypes
• deploy: python docker/scripts/perc-devctl.py qa-deploy-webui → RESULT:OK; qa-health again RESULT:OK
• Playwright: npm run test:surface -- --path tests/explorer-action-dispatch.spec.js → 5 passed (including Stage FORBIDDEN and Remove from Staging NOSTAGING_SERVERS); npm run test:golden → 2 passed
• console-clean=yes (Playwright pageerror listeners empty on staging tests)
• server.log-clean=yes (no staging/publish-related ERROR/FATAL in the test window)
• qa-down: RESULT:OK (this agent owned the cell)

Co-Authored by Grok Build 1.0.34 using grok-4.6 with agent night-issue-prs.

[natechadwick-intsof]

Human QA handoff: #4553 assigned to @vijaya-boddipudi (qa task). Verify Explorer Stage / Remove from Staging on merged PR #4551.

Co-Authored by Grok Build 1.0.34 using grok-4.6 with agent night-issue-prs-human-qa.