Accept string API keys in all connection helpers

[mimimind]

Summary

• align the remaining sync and async connection helper annotations with their documented runtime support for string API keys
• cover sync custom, async cloud, and async custom helpers without network access

Fixes #996.

Validation

• 11 related connection and authentication tests passed
• Ruff passed
• Flake8 passed
• Pyright passed

[orca-security-eu]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Infrastructure as Code	0   0   0   0	View in Orca
Passed	SAST	0   0   0   0	View in Orca
Passed	Secrets	0   0   0   0	View in Orca
Passed	Vulnerabilities	0   0   0   0	View in Orca

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[mimimind]

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