Fix the portfolio view's data regression

[JSONbored]

Problem: The portfolio view shows only a global aggregate, regressing versus the CLI's own richer per-repo dashboard (tracked as its own performance item above, since it's really a shared-data-path problem — this issue is the UI-facing half).

Area: AMS / Miner UI

Proposal: Once the shared data path exists (see the Performance category), update the portfolio view to render real per-repo detail.

Deliverables:

• A portfolio view showing per-repo breakdowns, not just a global count.

Boundaries:

• Depends on "Reunify the miner-ui portfolio view with the CLI's own richer dashboard" above.

Design system: whatever new per-repo markup this adds must use the shared design-system package from #4966/#4967, not the current ad hoc hardcoded classes.

[linear-code]

JSO-3514