refactor!: Make `Actor` initialization stricter and more predictable #669

Job	Run time
Lint check / Lint check (3.13)	13s
Lint check / Lint check (3.10)	14s
Type check / Type check (3.11)	25s
Docs check / Docs check	1m 0s
Lint check / Lint check (3.12)	11s
Type check / Type check (3.10)	30s
Type check / Type check (3.12)	27s
Lint check / Lint check (3.11)	10s
Unit tests / Unit tests (windows-latest, 3.12)	46s
Unit tests / Unit tests (windows-latest, 3.11)	47s
Unit tests / Unit tests (ubuntu-latest, 3.13)	26s
Type check / Type check (3.13)	25s
Unit tests / Unit tests (ubuntu-latest, 3.12)	24s
Unit tests / Unit tests (ubuntu-latest, 3.11)	18s
Unit tests / Unit tests (windows-latest, 3.10)	1m 11s
Unit tests / Unit tests (windows-latest, 3.13)	50s
Integration tests / Integration tests (3.13)	3m 22s
Unit tests / Unit tests (ubuntu-latest, 3.10)	35s
Integration tests / Integration tests (3.10)	3m 17s
Integration tests / Approve integration tests for PRs from forks	0s
Integration tests / Integration tests for PRs from forks	0s
	15m 31s

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