perf(viewer): expose history and selection on the ?perf probe

[Aymericr]

What does this PR do?

This adds two read-only methods to the ?perf scripted probe, window.__pascalPerf. The probe is mounted only when ?perf is in the URL.

• history() returns { past, future, tracking, pauseDepth }: undo and redo entry counts, whether scene history is recording, and the number of refcounted pause owners (pauseSceneHistory and leases). A direct temporal.pause() shows as tracking: false with pauseDepth: 0. That is the signature of the unbalanced item-move pause that building-fidelity A-12 fixes.
• selection() returns { buildingId, levelId, zoneId, selectedIds }.

Why: the private gesture receipts measure undo entries per gesture and whether history stays paused while an item is carried. Today they can only read those through dev-only store handles, so they cannot run against next start. This hook lets them. The logic is in lib/perf-probe-state.ts, with unit tests.

Nothing changes for the house: this is measurement only.

How to test

1. bun run --cwd packages/viewer test: 368 pass, 0 fail (3 new in perf-probe-state.test.ts).
2. Open any project with ?perf and run __pascalPerf.history() in the console. Move a wall, then run it again: past increases.

Checklist

• bun check: 2479 files, no fixes.
• check-types for @pascal-app/viewer passes. The workspace-wide run fails only in apps/editor on the missing optional @webxr/plugin module in this local checkout. That failure also happens without this change.
• This PR targets the main branch.

🤖 Generated with Claude Code

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Note

Low Risk
Read-only instrumentation behind the existing ?perf gate; no changes to scene history, selection, or viewer behavior.

Overview
Adds history() and selection() to the URL-gated window.__pascalPerf probe so scripted gesture receipts can read undo/redo counts, history tracking/pause state, and the current selection on production builds without dev-only store handles.

The logic lives in new perf-probe-state.ts: history() reports past, future, tracking, and refcounted pauseDepth (via getSceneHistoryPauseDepth), distinguishing direct temporal.pause() from pauseSceneHistory; selection() returns building/level/zone IDs and a copied selectedIds array. perf-monitor.tsx wires both into the existing probe object; unit tests cover pause semantics and selection immutability.

Normal sessions are unchanged—the probe still mounts only with ?perf.

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[pascal]

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