adding my information as a fellow (#2535)

* Add files via upload

* Add files via upload

* style: pre-commit fixes

* Update Lukka777.md

Date format for start and end dates should be – YYYY-MM-DD – i.e. 2025-12-31

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Rob Tuck <robtuck@gmail.com>

Author: 3 people

_fellows/2025/Lukka777.md

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+---
+layout: fellow
+pagetype: fellow
+shortname: Lukka777
+permalink: /fellows/Lukka777.html
+fellow-name: Luka Gavrysh
+title: Luka Gavrysh - IRIS-HEP Fellow
+active: True
+dates:
+  start: 2025-07-01
+  end: 2025-09-23
+photo: /assets/images/team/fellows-2025/Luka-Gavrysh.png
+institution: Taras Shevchenko National University of Kyiv
+e-mail: gavryshluka@gmail.com
+focus-area:
+challenge-area:
+projects:
+  - project_title: SW development for the Inner Tracker Data Trigger and Control system (IT-DTC)
+    project_goal: >
+      Develop and integrate pixel calibration routines into the CMS Inner Tracker online software.
+      The goal is to ensure accurate configuration, stability, and real-time performance of the detector under HL-LHC conditions.
+    mentors:
+      - Serhii Cholak (BU)
+      - Zeynep Demiragli (BU)
+      - Gianfranco De Castro (BU)
+    proposal: /assets/pdf/fellows-2025/UKR007-proposal-Luka-Gavrysh.pdf
+    presentations:
+      - title:
+        date:
+        url:
+        meeting:
+        meetingurl:
+        recordingurl:
+        focus-area:
+current_status: >
+  A placeholder for status updates
+github-username: Lukka777
+linkedin-profile:
+---