bug: Admin application lists use key={menteeId}; duplicate keys hide/mis-render cards

[yingliu-data]

Bug Report

Application list items use key={app.menteeId}, but a mentee can hold multiple applications per cycle, producing duplicate React keys that can hide or mis-render cards.

• admin-wcc-app/pages/admin/mentorship/index.tsx:215, 232, 249 and admin-wcc-app/components/mentorship/MentorApplicationsPanel.tsx:60 — key={app.menteeId}.
• The schema allows one application per (mentee, mentor, cycle) (V19__...create_mentee_applications_table.sql, UNIQUE (mentee_id, mentor_id, cycle_id)), so a mentee who applied to several mentors yields several items sharing the same key. applicationId is returned by the backend but unused.

Reproduction

Pending Review tab for a cycle where mentee 42 applied to two mentors → two cards with key=42 → React logs duplicate-key errors and may render only one card, or reconcile the wrong card when the list updates after accept/decline — hiding applications from the admin.

Severity

Medium

Potential Risk

• Admins can't see all applications; stateful updates (accept/decline) may mutate the wrong card.

Suggested Fix

• Use the unique applicationId as the React key everywhere these lists are rendered.
• Add a test/story with a mentee holding multiple applications and assert all cards render.