issue 4530 slice 20: Explorer display-format columns #4722

Parent: #4530

Slice goal

Operator changes list display-format columns for the current Explorer folder view; columns persist for the session/list. 400/403 mapped.

Out of scope

CX view execute (sibling). Workflow transitions (sibling).

Acceptance criteria

• Change display-format columns from Explorer list
• 400/403 mapped
• Playwright surface-filtered spec
• product-docs/8.2
• Update parent [8.2] Content Explorer — next product increments #4530 Agent progress

Change class

One vertical user-visible increment (REST + sitemanage + WebUI + Playwright + product-docs as needed). Do not split layers.

H2 QA: perc-devctl qa-up → qa-health → TEST_CMS_URL → npm run test:surface → qa-down.

Leave unassigned. Do not add In Progress.

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