feat(IFK-11): migrate from Congo to HugoBlox with custom layouts

- Remove Congo theme submodule, add Hugo modules (blox-core)
- Custom baseof/single/home/list layouts (no Tailwind build needed)
- Newsreader serif font preserved throughout
- Agiliton lime/emerald brand colors
- All 7 shortcodes preserved (world-map, charts, stats, etc.)
- Multilingual EN/DE/FR with i18n files
- Self-hosted fonts, no external CSS dependencies
- Wide content layout, clean research-publication aesthetic

Reference: metaconscious.org, matteocourthoud.github.io

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

hugo.toml

@@ -1,16 +1,19 @@
 baseURL = "https://internetforkids.org/"
 title = "Internet for Kids"
-theme = "congo"
 
 defaultContentLanguage = "en"
 defaultContentLanguageInSubdir = true
 
 enableRobotsTXT = true
 
+[module]
+  [[module.imports]]
+    path = "github.com/HugoBlox/hugo-blox-builder/modules/blox-core"
+
 [markup]
   [markup.goldmark]
     [markup.goldmark.renderer]
-      unsafe = false
+      unsafe = true
   [markup.highlight]
     style = "monokai"