fix(module-factory): LRU cache replacement triggers eviction

[d1r1]

• on_replace now allows LRU eviction instead of rejecting
• Add zero-size item rejection to prevent limit bypass
• Use saturating arithmetic to prevent overflow/underflow
• Assert max_bytes > 0 on construction
• Fix on_grow to always allow table growth
• Expand test coverage for edge cases

[github-actions]

Criterion results (vs baseline)

Heads-up: runner perf is noisy; treat deltas as a smoke check.