[nishantmonu51]

The pivot silently turns time comparison off once its columns hold more than 10 measures, with nothing in the UI explaining why. This raises the limit to 20.

• canEnablePivotComparison now reads a named MAX_PIVOT_COMPARISON_MEASURES constant (20) from pivot-constants.ts instead of a hard-coded 10. The canvas pivot uses the same function, so it picks up the new limit too.
• Adds unit tests for the gate: at the limit, one over the limit, dimension and time chips not counted, and no comparison range.

Steps to reproduce:

1. Open an explore dashboard whose metrics view has more than 10 measures and switch to the Pivot view.
2. Turn on time comparison and add 11 or more measures to the pivot columns.
3. Expected: every measure keeps its Δ and Δ% columns. Actual: the comparison columns disappear as soon as the 11th measure is added.

Checklist:

• Covered by tests
• Ran it and it works as intended
• Reviewed the diff before requesting a review
• Checked for unhandled edge cases
• Linked the issues it closes
• Checked if the docs need to be updated. If so, create a separate Linear DOCS issue
• Intend to cherry-pick into the release branch
• I'm proud of this work!

[djbarnwal]

Looks good