fix(issues): stop cold-load render loop on the Issues route (MUL-4985)

[NevilleQingNY]

What & why

The Issues route crashed with "Maximum update depth exceeded" on first paint (desktop_route_error on /…/issues). Root cause is a cold-load reference-instability loop, amplified by the real <Virtuoso> in the Board/Swimlane columns:

• While the member/agent/squad directory queries are still loading, useActorName's const { data: members = [] } defaults allocated a fresh array every render, so its getActorName memo changed identity each render.
• BoardView's groups memo and SwimLaneView's laneGroups list getActorName as a dependency, so they churned a new value every render.
• The board/list column-resync useEffect(setColumns, [groups, …]) then re-fired without end. react-virtuoso republishes its store synchronously on every render, which starves the query-resolution microtask and escalates the loop into the reported crash.

This is not a MUL-4797 regression — it reproduces at the parent commit and was exposed by the earlier board/swimlane virtualization reland (ea03912ba) that mounted a real <Virtuoso>; the latent getActorName instability predates that.

Changes

1. Root cause — packages/core/workspace/hooks.ts: share stable module-level empty arrays for the loading directory snapshot, so getActorName is referentially stable across cold-load renders (matches the existing EMPTY_* convention in the surface data hook).
2. Defense-in-depth — packages/views/issues/components/use-drag-settle.ts: equality-guard the shared column setter so a content-equal rebuild returns the previous reference and cannot spin the resync effect from any future unstable input. It only skips no-op writes; drag/settle semantics are unchanged.

workspaceProperties = [] was considered but left untouched: during cold load groupingProperty collapses to a stable null, so it does not churn the groups memo. groups is fully stabilized by fix (1).

Verification

• New regression tests (all red without the fix, green with it):
  • packages/core/workspace/hooks.test.tsx — getActorName is referentially stable across renders during cold load.
  • packages/views/issues/components/use-drag-settle.test.tsx — the column setter does not loop when a resync effect rebuilds a content-equal map every render, and still applies real content changes.
  • packages/views/issues/components/issues-cold-load-loop.test.tsx — Board (40 cards → real <Virtuoso>) and Swimlane (assignee grouping) render under pending directory queries with the real react-virtuoso. Without the fix the Board test fails with the exact issue error ("Maximum update depth exceeded"); with the fix both paint.
• Existing suites: packages/views issues tests 417 passed (incl. the 40+ swimlane drag tests exercising the guarded setter); packages/core workspace tests 19 passed.
• tsc --noEmit clean and eslint clean for packages/core and packages/views.

Closes MUL-4985

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Project	Deployment	Actions	Updated (UTC)
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