Add execution profile request workflow

[yoshifuminakamura]

Summary

Adds the CX Portal execution-profile request workflow.

• Adds authenticated applicant-facing profile requests at /execution-profile-requests/.
• Adds admin review at /admin/execution-profile-requests.
• Supports new_profile, change_profile, pause_profile, and retire_profile request types.
• Links approved requests back to current profile state and trigger counts in My Requests.
• Lets approvers convert requested schedule/watch targets into trigger definitions.
• Documents the workflow in the portal execution-profile handoff guide.

Operational Notes

Pause and retirement requests do not delete profiles. Approval disables the source profile and related trigger definitions, while preserving request/profile/result history.

Validation

• .venv/bin/pytest result_server/tests/test_execution_profiles.py -k "profile_request or execution_profile_requests"
• .venv/bin/python result_server/tests/run_result_server_tests.py

Both passed locally. The full result-server suite reported 384 passed with 5 existing deprecation warnings.