Keep headless/API auth options when adding additional accounts

[spidey000]

Summary

Detected Problem

• Adding a second+ OAuth account opened the browser flow immediately because authMethods collapsed to only browser OAuth once storage already contained entries, so headless/manual OAuth and API-key paths were unreachable.
• The auth login workflow test reinforced that behavior by asserting only a single method was exposed when accounts existed, preventing the desired UX from being guarded.

Proposed Solution

• Always offer the browser OAuth, headless/manual OAuth, and API-key login choices regardless of how many accounts are already stored.
• Update the workflow test to check for all three labels so regressions are caught.

Implemented Solution

• Removed the stored-account gate around the auth method list so [oauthMethod, manualOauthMethod, apiKeyMethod] is always returned.
• Adjusted test/auth-login-workflow.test.ts to expect the three labels even when fixtures contain existing accounts.

Testing

• npx vitest run test/auth-login-workflow.test.ts