[BUG] [Dashboard/Systems] - No registration path from global /systems view — UX dead-end in org-centric v2 model

## Bug Description
The `/systems` page (global cross-organizational systems view) does not provide a way to register a new system. There is no "+ Add System" button or any path to system registration from this view.

The v2 dashboard reorganized to an org-centric "flankspeed" model. Systems are now registered within an org's workspace. However, users landing on `/systems` (the default "Systems" nav link) see only a read-only cross-org table with no onward path to register a system. This creates a UX dead-end.

## Steps to Reproduce
1. Navigate to `https://ca-ato-copilot-dashboard-v2.../systems`
2. Observe: table of all systems across orgs
3. Look for a "Register System", "+ Add System", or "New System" button
4. Expected: button exists; Actual: no registration entry point present

## Expected Behavior
The `/systems` view should provide a path to register a new system, or clearly direct users to the correct org workspace to initiate registration (e.g., banner: "To register a system, navigate to your org workspace").

## Actual Behavior
No registration button or guidance. Page shows read-only cross-org system table only. The "Systems" nav item from the global header leads here, giving the impression this is the primary systems management surface, but registration is impossible from here.

## Screenshot
[Captured: Systems page with no Add System button — only filter/sort table]

## Console Errors
None — page loads successfully but registration functionality is absent.

## Browser/Environment
Azure Container Apps Dashboard (v2)
Browser: Chromium (Playwright/Hermes browser)
Date: 2026-07-06
Sweep: Automated 4-hour QA sweep

## Playwright Test Code
```typescript
test('[systems] no registration path from global systems list', async ({ page }) => {
await page.goto('/systems');
const addButton = page.locator('button:has-text("Add System"), button:has-text("Register")');
await expect(addButton).toBeVisible(); // FAILS — button does not exist
});
```

*Filed by Oracle — Automated 4-hour QA Sweep 2026-07-06T07:43:00Z*