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>

config/_default/params.toml

@@ -1,37 +1,18 @@
-colorScheme = "avocado"
+colorScheme = "light"
 defaultAppearance = "light"
 autoSwitchAppearance = false
 mainSections = [""]
 
+# Blox Core config
+minimal = false
+
 [header]
-  layout = "basic"
-  showTitle = true
+  navbar = true
 
 [footer]
-  showCopyright = true
-  showThemeAttribution = false
-  showScrollToTop = true
-  showAppearanceSwitcher = false
+  copyright = "© Internet for Kids"
+  privacyPolicy = "/privacy"
 
-[homepage]
-  layout = "profile"
-  showRecent = true
-  recentLimit = 5
-
-[article]
-  showDate = true
-  showReadingTime = true
-  showAuthor = true
-  showBreadcrumbs = true
-  showTableOfContents = true
-  showTaxonomies = true
-  showRelatedContent = true
-  showWordCount = false
-  showSummary = true
-
-[list]
-  showBreadcrumbs = true
-  showTaxonomies = true
-
-[taxonomy]
-  showTermCount = true
+[appearance]
+  color_theme = "ifk"
+  font_theme = "ifk_fonts"