Bump zot registry to v2.1.15

Upgrade from v2.1.13 to v2.1.15 for two security fixes:
- CVE-2025-30204 (golang-jwt excessive memory allocation)
- Open redirect via callback_ui

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/changelog.d/bump-zot-v2.1.15.infra.md

@@ -0,0 +1 @@
+Upgrade zot container registry from v2.1.13 to v2.1.15 (CVE-2025-30204, open redirect fix)

docs/reference/services/zot.md

@@ -1,6 +1,6 @@
 ---
 title: Zot
-modified: 2026-02-21
+modified: 2026-03-14
 tags:
   - service
   - registry

service-versions.yaml

@@ -269,8 +269,8 @@ services:
 
   - name: zot
     type: ansible
-    last-reviewed: null
-    current-version: null
+    last-reviewed: 2026-03-14
+    current-version: "v2.1.15"
     upstream-source: https://github.com/project-zot/zot/releases
     notes: Built from source on indri