Promote column bounds to the current schema in the scan reader, alongside partition tuples #3501

Is your feature request related to a problem or challenge?

Follow-up to #3483 (comment: #3483 (comment)).

After a partition source column is promoted (e.g. int -> long), values written under the older, narrower schema must be widened to the current type before they compare against predicates and delete-file partitions. #3483 does this in two different places:

• Partition tuples are widened once per entry in the scan reader
• Column bounds (lower/upper) are still widened lazily inside InclusiveMetricsEvaluator, at comparison time.

Two widening paths for the same underlying schema-evolution concern is harder to reason about and easier to get subtly wrong, as @Fokko and @mbutrovich noted on the PR. Partition tuples had to move to the reader because comparison-time promotion did not fix equality-delete / deletion-vector matching; bounds have no such forcing function (the metrics evaluator promotes them correctly on demand), so they were left in place to contain scope of #3483.

Describe the solution you'd like

Project column bounds to the current schema in the same per-entry loop that already normalizes partition tuples, so there is a single promotion point and the evaluators can drop their on-the-fly promotion

Scope: read/scan path only; no format or on-disk changes. Existing coverage in #3483 (partition widening + delete matching) should continue to pass unchanged; add bounds-pruning cases where a promoted column's bounds decide a file.

Willingness to contribute

I can contribute to this feature independently