Fix stale relations in stored Record values breaking renames (#2540)

## Context

When a formula returns a Record/RecordSet in an Any column, the stored
value carries a Relation object used for dependency tracking. Renaming
the table or column that holds that formula recomputes it, but the fresh
value compares equal to the stale one, so the stale object was kept.
Dependent formulas then failed with an AssertionError (table rename), or
silently stopped recalculating (column rename).

## Proposed solution

Fix at the recompute store gate: when a recomputed value looks unchanged
but is in an Any column, store it anyway, without reporting a change.

## Related issues

Fixes grist-core issue #2539.

## Has this been tested?

Test added, which fails on master and passes with this fix.

- [x] 👍 yes, I added tests to the test suite
- [ ] 💭 no, because this PR is a draft and still needs work
- [ ] 🙅 no, because this is not relevant here
- [ ] 🙋 no, because I need help <!-- Detail how we can help you -->