Manual leg-to-strategy tagging on imported options

Add a UI to manually group imported (or already-entered) option legs under a strategy label, so a user can say 'these two legs are my Bull Put Spread' and have them displayed as a single grouped row with combined realized P&L.

Context: the Options Dashboard already auto-detects multi-leg strategies for OPEN positions (verticals, iron condors, straddles, etc.) when legs share the same underlying and expiration. Closed positions, and any open strategy that auto-detection cannot cleanly infer (diagonals, calendars, mixed expiries), stay ungrouped today. There is no UI to fix that manually.

Suggested approach: select N legs, choose a strategy label, write it to the existing 'Strategy: X' comment convention that the Strategy Builder already uses. Detection then groups them at render time. No schema change required for a first pass.

Existing workaround: the 'Performance by Ticker' panel on the Options Dashboard (under Closed Positions, click Show) aggregates total realized P&L per underlying across all closed options. It's the closest current view, but not split by strategy.