feat(publish): Design content-list save (#4676)

[natechadwick-intsof]

Summary

PublishingShell Design: save content list (slice 14 of #4531). Operators create/update a content list from Design; dirty form is tracked; HTTP 403 (non-Admin/Designer) and 409 (duplicate name) map to the editor error region. REST body is JAXB-wrapped as { contentList } to match PSContentListSummary.

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

Parent: #4531

Test plan

• cd projects/sitemanage && rtk mvn clean install — BUILD SUCCESS, Tests run: 2919, Failures: 0
• cd WebUI && rtk mvn clean install — BUILD SUCCESS, Tests run: 69, Failures: 0
• H2 QA: perc-devctl qa-up TEST_CMS_URL=http://127.0.0.1:9993; qa-deploy-war-jars; qa-deploy-webui; qa-health HTTP 200
• Playwright: npm run test:surface -- --path tests/publishing/designContentListSave.spec.js — 2 passed; console-clean=yes
• server.log: prior 400 from unwrapped JSON during first QA attempt; successful save after wrap — no new feature ERROR on passing run (server.log-clean=yes for passing window)

Product documentation

• Updated product-docs/8.2/admin/publishing.md (Save a content list)

C3 evidence

• modules_built: projects/sitemanage,WebUI
• build_evidence: sitemanage rtk mvn clean install BUILD SUCCESS Tests run: 2919; WebUI BUILD SUCCESS Tests run: 69
• downstream_checked: none (no public type sealed/final; no rest interface signature change)

Fixes #4676

Co-Authored by Grok Build 1.0.40 using grok with agent night-issue-prs.

[natechadwick-intsof]

Erlang review (strict). Status: cli-unavailable, manual review.

Scope: #4676 Design content-list save 403/409, JAXB wrap, dirty form.

Hard gates: PSPublishingDesignRestService 403/409 tests; mapContentListSaveError + editor tests; Playwright; product-docs. No rule files.

No bugs. Recommendation: approve.

Co-Authored by Grok Build 1.0.40 using grok with agent night-issue-prs-erlang.