Add Enhua Zhu to CONTRIBUTORS.md

[ezhu001]

Objective and plan

Introduction-only PR for M1 onboarding. Adds my roster row to CONTRIBUTORS.md following docs/student-start.md steps 2–3.

Closes #47
Relates to #5

Change

Adds one row to the roster: Enhua Zhu / @ezhu001.

Introduction

M.S. in Financial Engineering at NYU Tandon 2nd Year.

Review

• The issue's acceptance criteria are addressed, or remaining work is explicitly linked.
• Evidence and contribution credit are accurate and reviewable.
• Changes to scope, methods, or decisions are reflected in the canonical plan/log when applicable.

[zhongnz]

Maintainer review (tool-assisted) of 51f9794f92b01ff983e26e26fa95bf5f14228ac5: the net change is one alphabetically placed roster row for Enhua Zhu / @ezhu001, with a matching HTTPS GitHub profile link. The original student commit 8f42520c954a7ada164cdf75e35492ceae8cdb8f remains in history; maintainer integration only handles the current base, roster order and link formatting.

The linked task is an onboarding contribution under #5, with no separate research grade. No experiment, grading, permission or workflow settings changed. Required CI must pass on this revision before the normal protected-branch merge. Only this student's onboarding task should close; #5 stays open for the cohort.

Corrected the copied profile URL in this PR description; the submitted roster row already pointed to @ezhu001.