feat: cache alpha powers in static verifier

[yi-sun]

Base benchmark: https://github.com/openvm-org/openvm/blob/benchmark-results/benchmarks-pr/1175/fib_e2e-df279c459194c4a0e49469eeb1b15d1427a9b233.md

New benchmark: https://github.com/openvm-org/openvm/blob/benchmark-results/benchmarks-pr/1238/fib_e2e-c710bdc3f383aceed4ae546933cba5cbdb898e19.md

[github-actions]

group	app.proof_time_ms	app.cycles	app.cells_used	leaf.proof_time_ms	leaf.cycles	leaf.cells_used
verify_fibair	(+12 [+0.4%]) 3,393	711,682	25,523,334	-	-	-
fibonacci_program	(+23 [+0.4%]) 6,094	1,500,137	51,505,102	(+110 [+0.8%]) 13,355	3,085,332	110,719,808
regex_program	(+85 [+0.4%]) 19,057	4,190,904	165,028,173	30,662	5,934,513	244,157,511
fib_e2e	41,815	12,000,137	410,820,430	88,666	18,478,671	661,103,859
ecrecover_program	(-12 [-0.5%]) 2,618	285,401	15,092,297	(+1308 [+3.2%]) 42,685	8,652,418	365,885,227

Commit: 0116fae

Benchmark Workflow

[jonathanpwang]

LGTM