WIP: Explore reshape-aware dynamic padding buckets

[stevenvar]

Summary

This WIP explores padding dynamic input dimensions while preserving divisibility requirements used by internal shape expressions.

Dynamic padding buckets inspect dynamic Reshape output expressions and align the selected compile batch with their constant divisors. For example, an internal A / 12 reshape selects 384 rather than 512 for a runtime value of 300.

Tests

• Checks the existing next-power-of-two behavior without alignment.
• Checks that A / 12 selects divisible buckets.
• Checks that independent divisors such as 12 and 18 are combined.

WIP limitations

The prototype currently scans the cluster function during compilation and only reads Reshape output-shape expressions. Before making this ready, the analysis should be computed once during clustering and stored as cluster metadata. It also needs a more general treatment of shape-derived value paths such as Shape -> arithmetic -> Fill/Tile.