fix: Add constraint that initial timestamp must be zero

[zlangley]

No description provided.

[github-actions]

group	app.proof_time_ms	app.cycles	app.cells_used	leaf.proof_time_ms	leaf.cycles	leaf.cells_used
verify_fibair	(+66 [+5.3%]) 1,305	334,162	17,905,347	-	-	-
fibonacci_program	(+103 [+3.9%]) 2,763	1,500,096	51,485,167	-	-	-
regex_program	(-266 [-3.3%]) 7,747	4,140,164	167,389,450	-	-	-
ecrecover_program	(+45 [+3.1%]) 1,477	295,291	15,588,656	-	-	-
pairing	(+8 [+0.2%]) 4,715	1,711,640	92,585,975	-	-	-

Commit: fd5b728

Benchmark Workflow

[jonathanpwang]

lgtm