feat(share-pnl): redesign card and add field toggles

[kostovster]

Summary

Redesigns the Share PnL dialog so text now sits directly on the cover illustration rather than inside a white block. Adds three optional fields the user can include or omit: PnL Amount, Price (Entry + Mark), Position Size — all default on.

Changes

• Removed the white card overlay drawn by canvas plus the matching divider lines. Cover 1's SVG had the same shape baked in, so cleared it from the asset too — otherwise the outline would have remained after the canvas-side card was removed.
• Per-cover text palette so text stays legible on each illustration. Cover 2 uses light text on its dark navy backdrop; covers 1, 3, 4 keep the existing dark navy text.
• New Checkbox row in the dialog body for the three field toggles, wired into the canvas via a reactive watch.
• scheduleRender now chains renders per canvas through a WeakMap. Without it, a toggle flip during an in-flight image.onload could let stale paints from a prior render land on a newer frame, leaving ghost rows visible after toggling a field off.
• Four new keys in backend/config/locales/en.json: optional-info-share, pnl-amount, entry-price, mark-price. The runtime translation pipeline propagates the rest.

Verification

• npm run lint clean
• npm run format:check clean
• npm run build clean
• npm test 760/760 passing

Follow-ups

• Add the four new keys with English values to /opt/deploy/builds/{app,app-dev}/config/locales/en.json on the frontends server (rclone sync excludes config/), then restart webapp-prod and webapp-dev so the in-memory cache picks them up.