fix: prefill administrator role for local Docker login

[jQuinRivero]

Summary

Prefill the administrators role in the Azure Static Web Apps mock-login portal used by Docker Compose. Local users can now enter a user ID and username and log in without knowing that they must manually add the HASTE administrator role.

The change is isolated to the SWA CLI installed inside the local UI Docker image. Production authorization and the source staticwebapp.config.json remain unchanged.

Changes

• Patch the Docker image's SWA mock-login portal to include administrators in its default roles.
• Merge the default roles into cached emulator profiles so existing local browser sessions also receive administrators.
• Fail the image build if the expected SWA portal structure changes instead of silently losing the default.
• Update the quickstart, Docker, local-development, and configuration documentation to describe the new login flow.

Testing

• Built the UI Docker image locally.
• Verified the served SWA login page pre-fills anonymous, authenticated, and administrators.
• Verified a browser profile that had cached the old role list receives administrators.
• Completed a mock login through the isolated UI container.
• cd ui && npm run build
• Formal pre-landing review completed with no findings.
• cd ui && npm run lint is blocked by the repository's existing ESLint 9 configuration mismatch (eslint.config.js is not present).

Review Notes

The Docker build performs a guarded replacement against the installed SWA CLI asset. If a future SWA CLI release changes that asset, the build fails with Unexpected SWA auth portal so the local authentication behavior cannot regress silently.

[mgmachado]

LGTM