Feature: Add a treasury balance dashboard

[Mosas2000]

Summary: Build a dedicated dashboard section for treasury health, inflows, and funding availability.

Why it matters: Treasury visibility helps users understand whether proposals are realistically fundable and whether the DAO is healthy enough to support new requests.

Scope:

• Show the current treasury balance.
• Surface recent inflows and changes over time.
• Keep the view lightweight so it can load quickly alongside the rest of the app.

Acceptance notes:

• Treasury status is visible without opening a separate tool.
• The dashboard clearly distinguishes balance from activity.
• The data source is consistent with proposal creation and execution.