fix: DAH-4340 Apply button

[jimlin-sfgov]

Description

Fix the apply button on the listing details page.

Jira ticket

https://sfgovdt.jira.com/browse/DAH-4340

Before requesting eng review

Version Control

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• branch name contains the Jira ticket number
• PR name follows type: TICKET-NUMBER Description format, use DAH-000 if it does not need a ticket
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Code quality

• the set of changes is small
• all automated code checks pass (linting, tests, coverage, etc.)
• if the PR is a bugfix, there are tests and logs around the bug

Code conventions

• web pages are formatted with .scss stylesheets and ui-seeds tokens, rather than inline styles or Tailwind

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[Copilot]

🟡 Changes recommended

A newly added assertion hard-codes a non-localized apply URL even though production code uses localizedPath, which can make the test locale-sensitive/flaky.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR fixes the “Apply Online” button behavior on the listing details page when Clerk auth is enabled by ensuring the button links to the correct destination (sign-in, add-profile, or the application flow) instead of rendering with an empty/invalid href.

Changes:

• Refactors Clerk-gated apply-link selection to use explicit early returns for loading/signed-out/profile-missing states.
• Adds/updates unit tests for Clerk-enabled apply button routing behavior, including auth-loading behavior.
• Minor import cleanup in the SignIn flow test.

File summaries

File	Description
app/javascript/modules/listingDetailsAside/ListingDetailsApply.tsx	Fixes apply button href selection under Clerk auth by handling loading/signed-in/profile states explicitly.
app/javascript/tests/pages/SignInFlow.test.tsx	Consolidates constants import (no functional behavior change).
app/javascript/tests/modules/listingDetailsAside/ListingDetailsApply.test.tsx	Adds coverage for Clerk-enabled apply button redirect behavior and auth-loading non-render case.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 1
• Review effort level: Lite

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[Copilot]

🟢 Approval recommended

The change is small, fixes a concrete bad-link state, and is backed by focused tests for the updated Clerk apply-button logic.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 0 new
• Review effort level: Lite