[BUG] [RMF Roles] - Assign RMF Roles modal blocked: 'No Person components found in Component Library' — role assignment impossible through UI

## Bug Description

The **Assign RMF Roles** modal in the system Overview page (Phase Readiness section) opens correctly, but the **"Assign Role"** button is permanently disabled because there are **no Person components available** in the Organization Component Library.

The modal shows:
- Role dropdown: `Authorizing Official (AO)`, ISSM, ISSO, SCA, System Owner (all functional)
- Person search field: `"Search person components..."` → `"No Person components found in the Component Library."`
- Assign Role button: **disabled** (grayed out, cannot click)

There is no in-UI path to add Person components to enable role assignment. The modal is a dead-end.

## Steps to Reproduce

1. Navigate to any system overview page (e.g., `/systems/b5defa27-6258-421f-a09d-c7fc8c5bb105`)
2. Click "**Assign →**" next to "RMF Roles Assigned" in Phase Readiness section
3. Modal opens with "Assign RMF Roles"
4. Select a role from dropdown
5. Observe: "No Person components found in the Component Library" message
6. Observe: "Assign Role" button permanently disabled

## Expected Behavior

The user should be able to assign a person to an RMF role, either by:
- Selecting from a list of users/people registered in the org, OR
- Entering an email/UPN directly, OR
- Being navigated to where they can add Person components

## Actual Behavior

The `"Assign Role"` button is disabled because there are no Person components. There is no way to add Person components from this modal. The user is stuck.

## Impact

- **RMF Phase Readiness cannot be completed** — "RMF Roles Assigned" prerequisite is permanently blocked
- Advancing from Prepare to Categorize requires at least 1 RMF role, which is now impossible through the UI
- This affects ALL systems in the org

## Related Issues

- Closed #497 (HTTP 405 on role assign) — that was fixed, but this new blocker emerged
- The modal itself now correctly renders (progress from #497)

## Screenshot

Modal shows role dropdown populated but "Assign Role" grayed out with "No Person components found in the Component Library."

## Console Errors

None visible.

## Browser/Environment

Azure Container Apps Dashboard (`-v2`)
Browser: Chromium (Playwright/Hermes browser)
Date: 2026-07-01T00:58:00Z
Sweep: Automated 4-hour QA sweep

*Filed by Oracle — Automated 4-hour QA Sweep 2026-07-01T00:58:00Z*