fix: correct na_handling "propagate" typo in weighted_interval_score docs

[SatvikMishra08]

Checklist

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Change explanations for reviewer

The roxygen for weighted_interval_score() documented na_handling = "propogate", but the implemented choices use "propagate". Copying the documented value fails arg_match. This PR fixes the typo in R/weighted_interval_score.R, regenerates man/weighted_interval_score.Rd, and bumps 0.2.7 → 0.2.8 with a NEWS entry.

Magic GitHub syntax to mark associated Issue(s) as resolved when this is merged into the default branch

• Resolves weighted_interval_score() docs typo: na_handling = "propogate" (the valid value is "propagate"`) #495