feat: add passkey support

[RWayne93]

Been a long time user of Supabase and wanted to give something back. I've seen some workarounds here and there for passkey's with Supabase but just wanted to have it directly in auth instead.

Below is a video showing a simple login page with a protected dashboard view demonstrating passkeys on ios using bitwarden to store the private key.

ScreenRecording_10-21-2025.21-54-16_1.MP4

[chadpenny]

+1

[hf]

Thank you for the contribution. Be aware that the team is a bit stretched with some ongoing priorities so there'll be a delay until we review this properly.

Like other contributions, adding the code to the server is half the work and we'd need to schedule both a security review and productize the feature (add it to the dashboard, docs, support playbooks, etc.) so it will take a bit of time.

[coveralls]

Pull Request Test Coverage Report for Build 18765549909

Details

• 30 of 520 (5.77%) changed or added relevant lines in 9 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-1.6%) to 65.975%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/api/mfa.go	3	4	75.0%
internal/models/errors.go	0	5	0.0%
internal/api/admin.go	0	17	0.0%
internal/models/user.go	1	28	3.57%
internal/models/factor.go	3	31	9.68%
internal/models/passkey_challenge.go	0	37	0.0%
internal/api/passkey.go	0	375	0.0%

Totals
Change from base Build 18655410402:	-1.6%
Covered Lines:	13474
Relevant Lines:	20423

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💛 - Coveralls