Prevent duplicate submissions with guard flags

[Copilot]

Clicking submit buttons once was triggering 40-50 duplicate submissions.

Changes

Added guard flags to three submission handlers:

• Code submission (submitpage.php): isSubmitting flag prevents concurrent Submit/PassCheck operations
• Discussion posts (newpost.php): isSubmittingPost flag guards post creation
• Discussion replies (thread.php): isSubmittingReply flag guards reply submission

Each flag checks at handler entry and returns early if already submitting, then resets on all exit paths (validation failures, API errors, success).

let isSubmitting = false;
Submit.addEventListener("click", async () => {
    if (isSubmitting) return;
    isSubmitting = true;
    // ... validation and submission logic
    isSubmitting = false; // reset on all completion paths
});

Note: isSubmitting scoped before PassCheck handler since Submit calls PassCheck.click() programmatically after validation.

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

---

Summary by cubic

Fixes multiple submissions triggered by a single click across code submit, new post, and reply. Ensures only one request runs at a time and the UI reflects the pending state.

• Bug Fixes
  • Add per-form submission flags (isSubmitting, isSubmittingPost, isSubmittingReply) with early-return guards.
  • Disable submit buttons and show loading during requests; reset flags on success, validation failures, and errors.

^{Written for commit cb60e33. Summary will update on new commits.}

[github-actions]

请向dev分支提交pull request, 本pull request将被自动关闭