fix(staggered): CS panel reg/ipw influence functions + per-cell SEs t… #2654

Job	Run time
Pure Python Fallback	1h 27m 21s
Rust Unit Tests (macos-latest)	1m 16s
Rust Unit Tests (ubuntu-latest)	1m 16s
Python Tests (macos-latest, py3.11)	29m 30s
Python Tests (windows-latest, py3.14)	1h 0m 45s
Python Tests (ubuntu-24.04-arm, py3.13)	35m 55s
Rust Unit Tests (windows-latest)	2m 15s
Python Tests (windows-latest, py3.11)	57m 34s
Python Tests (ubuntu-24.04-arm, py3.14)	35m 0s
Python Tests (ubuntu-latest, py3.11)	1h 5m 47s
Rust Unit Tests (ubuntu-24.04-arm)	1m 19s
Python Tests (windows-latest, py3.13)	59m 55s
Python Tests (ubuntu-24.04-arm, py3.11)	39m 23s
Python Tests (macos-latest, py3.14)	35m 58s
Python Tests (ubuntu-latest, py3.13)	1h 3m 38s
Python Tests (ubuntu-latest, py3.14)	1h 4m 41s
Python Tests (macos-latest, py3.13)	36m 34s
	11h 18m 7s

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