Add E2E regression coverage for app launch options through intermediate modals

[nowgnuesLee]

Summary

FR-3343 fixed open_to_public / allowed_client_ips / port being dropped when launching apps that go through an intermediate modal (TensorBoard path modal, nniboard / mlflow-ui confirmation modal). Copilot review on PR #8327 pointed out that current E2E coverage cannot catch this class of regression:

• e2e/app-launcher/app-launcher-launch.spec.ts only asserts proxy parameters on the direct ttyd path, and only negatively (asserts the params are absent when options are unset).
• There is no positive test that sets "Open app to public", allowed client IPs, and a preferred port, then asserts the proxy /add request carries open_to_public=true, allowed_client_ips, and port.
• The AppLauncherModal E2E helper class has no methods for the option checkboxes/inputs or the follow-up modals.

Scope

1. Extend the AppLauncherModal helper with option controls (open-to-public checkbox, client IPs input, preferred port input) and follow-up modal interactions (TensorBoard path submit, confirmation modal confirm).
2. Positive direct-path test: launch with all options set, assert all three proxy parameters (Test Plan §5.2).
3. TensorBoard path: set options → click tensorboard → submit path modal → assert parameters survive (requires session image exposing the tensorboard service port; gate with @requires-app-tensorboard).
4. Confirmation path: same for nniboard / mlflow-ui (gate with appropriate @requires-app-* tags; these may only be testable via preopen ports).

References

• PR fix(FR-3343): pass open-to-public and preferred-port settings through to TensorBoard and confirmation app launches #8327 Copilot comments (regression-coverage requests)
• e2e/AppLauncher-Test-Plan.md §5.2 — scenarios already documented but unimplemented
• FR-3343 — the regression this coverage should prevent from recurring

JIRA Issue: FR-3345