fix(react): preserve scroll authority across anchored rebuilds

[blove]

Summary

• establish an explicit two-way scroll-authority protocol between the grid/DOM and row-layout controller
• propagate controller anchor adjustments through grid state to the real scroll element before paint
• suppress causal viewport echoes while preserving current-position behavior for semantic sort, filter, and grouping changes
• share the row-model's exact semantic-query equality through an internal subpath
• add controller-level and DOM integration regression coverage

Root cause

After an anchored controller rebuild, a controller status publication retriggered the viewport-feed effect. The effect treated the unchanged, pre-anchor grid offset as a fresh input and overwrote the controller's anchor-adjusted scroll position.

Verification

• React: 117 files, 1,644 tests passed
• row-model: 42 files, 719 tests passed
• benchmark app: 181 tests passed
• focused authority/navigation set: 4 files, 38 tests passed
• all six website tests that timed out during a machine-load above 70 parallel run passed serially; the remaining three passed with one worker and a 120-second timeout
• typecheck, public typecheck, type-performance budgets, lint, format, production build, API Extractor, publish preflight, packaging, consumer bundling, React compatibility, and security audit passed

Fixes #524

[vercel]

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
pretable	Ignored		Aug 30, 2026 11:39pm

[github-actions]

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