feat(oidc): enhance SSO target app resolution and audit logging

- Updated targetAppFromReturnTo function to handle OIDC authorization unwrap and added search parameter processing.
- Integrated target app resolution into the OIDC route for improved audit logging of SSO handoffs.
- Added a test case to verify the logging of the target app during the authorization process.
- Updated documentation to reflect changes in audit logging for the Technitium DNS application.

Co-authored-by: Cursor <[email protected]>

apps/api/test/target-app.test.ts

@@ -0,0 +1,24 @@
+import { describe, expect, it } from 'vitest'
+import { targetAppFromReturnTo } from '../src/lib/target-app.js'
+
+describe('targetAppFromReturnTo', () => {
+  it('maps dns host and /sso/ path', () => {
+    expect(targetAppFromReturnTo('https://dns.shnt.top/sso/callback')).toBe(
+      'dns',
+    )
+  })
+
+  it('unwraps portal /oauth/authorize return_to via redirect_uri', () => {
+    const returnTo =
+      'https://auth.shnt.top/oauth/authorize?client_id=abc&redirect_uri=' +
+      encodeURIComponent('https://dns.shnt.top/sso/callback') +
+      '&response_type=code&scope=openid'
+    expect(targetAppFromReturnTo(returnTo)).toBe('dns')
+  })
+
+  it('keeps portal for bare issuer authorize without redirect_uri', () => {
+    expect(
+      targetAppFromReturnTo('https://auth.shnt.top/oauth/authorize'),
+    ).toBe('portal')
+  })
+})