feat: add GA4 login event tracking

[MillenniumFalconMechanic]

Ticket

Closes #913

Summary

• Add GA4 login event (recommended event) that fires when a user authenticates via Google Sign-In
• Track the false → true transition of isAuthenticated in both auth providers (GoogleSignInAuthenticationProvider and NextAuthAuthenticationProvider)
• Gate tracking on AUTH_STATUS.SETTLED to prevent false positives during session hydration
• Use existing tool_name custom dimension (instead of method) to avoid provisioning a new GA4 dimension

Test plan

• Unit tests pass (useLoginTracking.test.ts — 6 cases covering mount, transition, logout, and hydration scenarios)
• Run AnVIL CMG locally, sign in, and verify window.dataLayer contains { event: "login", params: { tool_name: "google" } }
• Verify the event does not appear on page refresh when already signed in

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Adds GA4-recommended login analytics tracking to the @databiosphere/findable-ui auth flows so consuming apps automatically emit a login event when authentication completes (without firing on initial mount for persisted sessions).

Changes:

• Added EVENT_NAME.LOGIN and EVENT_PARAM.METHOD (plus typed params) to the analytics entities.
• Introduced useLoginTracking(isAuthenticated) hook to detect false → true authentication transitions and send track("login", { method: "google" }).
• Wired useLoginTracking into both GoogleSignInAuthenticationProvider and NextAuthAuthenticationProvider, and added unit tests for the hook.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/useLoginTracking.test.ts	Adds unit coverage for initial mount vs. auth transitions for the login tracking hook.
src/nextauth/provider.tsx	Invokes login tracking based on authState.isAuthenticated in the NextAuth provider.
src/hooks/authentication/useLoginTracking.ts	New hook that tracks GA4 login on false → true isAuthenticated transitions.
src/google/provider.tsx	Invokes login tracking based on authState.isAuthenticated in the Google Sign-In provider.
src/common/analytics/entities.ts	Extends analytics enums and event-param typing to include GA4 login with method.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 7 comments.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.