perf(mobile): bound the parsed review cache (#9749)

Bound cached parsed review sections by eight entries and 4,194,304 full source characters. Evicted inactive parsed and native results can be collected. Raw patches, comments, and view state stay unchanged.

Prewarm only nearby sections that fit beside the selected section. Use actual retained source weights for normalized cache hits, and skip oversized prewarms.

Created with GPT-6 Astra (preview) in Codex.