chore: pull loop unrolling refactor from sync PR

[TomAFrench]

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Changes to circuit sizes

Generated at commit: 912c6ebaa46de3a6e38e33e75fc1c63e3717b29a, compared to commit: 10c64fccae2205a0cfde3162b96ceca57aa5a177

🧾 Summary (100% most significant diffs)

Program	ACIR opcodes (+/-)	%	Circuit size (+/-)	%
rollup_base_private	+176 ❌	+0.05%	+176 ❌	+0.01%
rollup_base_public	+176 ❌	+0.04%	+176 ❌	+0.00%
rollup_root	+4 ❌	+0.03%	+4 ❌	+0.00%
rollup_block_merge	+4 ❌	+0.03%	+4 ❌	+0.00%

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Full diff report 👇

Program	ACIR opcodes (+/-)	%	Circuit size (+/-)	%
rollup_base_private	335,238 (+176)	+0.05%	3,409,577 (+176)	+0.01%
rollup_base_public	472,505 (+176)	+0.04%	3,745,930 (+176)	+0.00%
rollup_root	11,993 (+4)	+0.03%	1,858,510 (+4)	+0.00%
rollup_block_merge	12,009 (+4)	+0.03%	1,858,524 (+4)	+0.00%