Per-ticker equity curve on stock detail page

Add a chart on the per-ticker stock detail page showing cumulative position P&L (or position value) over time, including option legs on the same underlying.

Today the chart on the stock detail page shows the underlying's market price history, which works as an equity curve for plain stock holdings but does not reflect any of the options activity on that ticker. Portfolio-level equity curves exist on the stock dashboard, but not per ticker.

Especially useful for options-heavy positions (Poor Man's Covered Calls, diagonals, calendars) where buying back short calls plus weekly premium plus the long leg's mark-to-market are what define the equity curve and the underlying's price chart alone does not capture it.

Open questions worth discussing in the comments:
- Should the chart show realized P&L only, or include unrealized too?
- Per-ticker only, or also per-strategy (one curve per PMCC cycle)?
- Time-range controls similar to the existing portfolio chart.