## Summary
- Adds a **Monthly / Daily granularity toggle** to the account balance
evolution chart on account pages
- Daily view renders as an **area chart** (line with gradient fill)
showing the last 30 days, while monthly keeps the existing bar chart
- All 3 chart view modes (stacked, period-over-period,
period-over-period %) work in both granularities
- Chart view toggle **tooltips update dynamically** based on granularity
(e.g. "Month over month change" → "Day over day change")
- Backend fills gaps in sparse `account_balances` data by carrying
forward the last known balance day-by-day
- Includes 3 new Pest tests for the daily endpoint (data points,
gap-filling, forbidden access)
## Screenshot
<img width="1271" height="743" alt="image"
src="https://github.com/user-attachments/assets/cca7a7ad-bdcc-45d2-a5e1-47b1cb855d49"
/>
<img width="1274" height="755" alt="image"
src="https://github.com/user-attachments/assets/14e1f2d8-41cd-49cc-b0f4-307edb847af8"
/>