test: add stream route E2E tests with detail page flows

[DSingh0304]

Why submit this pull request?

• [ ] Bugfix
• [x] New feature provided
• [ ] Improve performance
• [ ] Backport patches

What changes will this PR take into?

This PR adds comprehensive E2E test coverage for Stream Routes, which was previously missing from the test suite.

Changes:

• Add stream_routes.crud-required-fields.spec.ts for minimal CRUD operations testing
• Add stream_routes.crud-all-fields.spec.ts for extended CRUD with optional fields (server_addr, remote_addr, SNI, labels)
• Add stream_routes.list.spec.ts for pagination testing
• Create e2e/utils/ui/stream_routes.ts helper module for stream route form interactions
• Update stream_routes POM with isIndexPage, isAddPage, isDetailPage assertions and navigation helpers

Test Flow: All CRUD operations now use the detail page for edit/delete workflows instead of relying on non-existent list-page Edit buttons. Tests verify:

• Creation automatically lands on detail page (read-only view)
• Editing works via detail page Edit button
• Deletion happens through detail page dialog with proper list verification
• Pagination and list view functionality works correctly

Related issues

fix #3084

Checklist:

• [x] Did you explain what problem does this PR solve? Or what new features have been added?
• [x] Have you added corresponding test cases?
• [ ] Have you modified the corresponding document?
• [x] Is this PR backward compatible? If it is not backward compatible, please discuss on the mailing list first

[DSingh0304]

Fixed e2e flakiness: added retry to src/apis/upstreams.ts::deleteAllUpstreams and increased timeouts in stream_routes.ts. I ran CI=true pnpm e2e locally all 27 tests passed.

[SkyeYoung]

Also pls fix tests

[DSingh0304]

The CI is fixed; all tests are passing locally.