Added direct Submission for CodeChef & Atcoder with CPH and linked with CPH-submit

[sachin-prmndani]

feat: Add CodeChef & Atcoder Submission Support via cph-submit

closes #672
closes #681

Overview

This PR adds CodeChef & Atcoder problem submission support to CPH, complementing the corresponding changes in the cph-submit extension (PR #40). The changes on the CPH side are intentionally minimal — the heavy lifting (language selection, editor injection, CSP bypass) is handled entirely by cph-submit.

Changes

• App.tsx — Conditionally renders the Submit button for CodeChef & Atcoder problems, consistent with the existing Codeforces submission UI.
• storeSavedProblems — Added a submitCodeChef() & 'submitAtcoder()' function that stores the necessary problem metadata, making it available for cph-submit to pick up and trigger the submission flow.

Workflow

The full end-to-end submission workflow (language mapping, Ace editor injection, Chrome MV3 CSP bypass) is documented and implemented in the cph-submit counterpart: agrawal-d/cph-submit#40

CodeChef Problem:

Atcoder Problem:

[feynmansfan]

Can you add AtCoder too,

[sachin-prmndani]

Can you add AtCoder too,

I tried but Cloudfare is making it nearly impossible todo.

Edit:
@feynmansfan done.

[sachin-prmndani]

@agrawal-d I added the AtCoder support to this PR itself because I ran into merge conflicts when trying to open a separate PR. Sorry for the inconvenience.