Enhance TP/SL input UX

[its-amann]

Summary

• Adds a shared TP/SL calculation helper for target/trigger price, P/L percent, and P/L amount.
• Adds quick limit/stop price preset buttons plus TP/SL preset buttons in the order form.
• Adds synchronized profit/loss amount inputs and summaries for take-profit and stop-loss without changing order submission semantics.

Verification

• npm ci
• npm run test:tpsl
• npm run build
• git diff --check
• Browser smoke on http://127.0.0.1:5000/trade: Options expands and the new Limit/Stop, Take-Profit, and Stop-Loss controls render in the order form.

Build completes with the existing Svelte/Rollup warnings already present in this codebase.

Refs #17.

I requested assignment/consideration on the issue before opening this PR. I can provide payout details privately if this PR is selected.

[its-amann]

Status note after opening: the only GitHub commit status currently failing is Vercel, and its description is Account is blocked. with the Vercel account-blocked knowledge-base link. That appears to be a deployment account/configuration issue rather than a code build failure.

Local verification for this branch completed with:

• npm run test:tpsl passing 3/3 tests
• npm run build completing successfully
• git diff --check exiting 0

[its-amann]

@devgreek since issue #17 mentions assignment as part of eligibility, could you confirm whether this PR can be considered for the bounty?

I kept the implementation focused on the order-entry TP/SL UX and added a separate calculation helper with local regression tests. The current failing GitHub status is Vercel reporting Account is blocked., while the branch passes the local build/test checks listed in the PR body.

[devgreek]

@its-amann This project is already dead, the main dev has abandoned it for years now