fix(collections): update Full Wikipedia URL to current Kiwix mirror

The 2024-01 all_maxi ZIM was removed from Kiwix mirrors, causing
silent 404 failures for users selecting "Complete Wikipedia (Full)".
Updated to 2026-02 release (115 GB).

Closes #216

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

Author: 2 people

collections/wikipedia.json

@@ -1,5 +1,5 @@
 {
-  "spec_version": "2026-02-11",
+  "spec_version": "2026-03-23",
   "options": [
     {
       "id": "none",
@@ -45,9 +45,9 @@
       "id": "all-maxi",
       "name": "Complete Wikipedia (Full)",
       "description": "The complete experience with all images and media.",
-      "size_mb": 102000,
-      "url": "https://download.kiwix.org/zim/wikipedia/wikipedia_en_all_maxi_2024-01.zim",
-      "version": "2024-01"
+      "size_mb": 115000,
+      "url": "https://download.kiwix.org/zim/wikipedia/wikipedia_en_all_maxi_2026-02.zim",
+      "version": "2026-02"
     }
   ]
 }