fix(cms): add fallbackLocale and fix broken SL homepage links

Adds fallbackLocale: 'en' so Slovenian locale falls back to English for
pages that have no SL translation (architecture, install, operate, etc.).
Fixes root index.md links from non-existent /namestitev/ and /arhitektura/
slugs to the real /install/ and /architecture/ paths.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---
Build: pass | Tests: FAIL — Tests  8 failed | 2009 passed (2017)

bootstrap/cms/clawdie-site/src/astro/astro.config.mjs

@@ -89,6 +89,7 @@ export default defineConfig({
           lang: 'en',
         },
       },
+      fallbackLocale: 'en',
       sidebar,
     }),
   ],

bootstrap/cms/clawdie-site/src/content/docs/index.md

@@ -14,6 +14,6 @@ Clawdie je osebni AI asistent, ki teče nativno na FreeBSD prek Bastille jailov
 
 ## Začni
 
-- [Namestitev](/namestitev/) — korak po korak do prve namestitve
-- [Arhitektura](/arhitektura/) — kako je sistem zasnovan
+- [Namestitev](/install/) — korak po korak do prve namestitve
+- [Arhitektura](/architecture/) — kako je sistem zasnovan
 - [Dokumentacija (EN)](/en/) — tehnična dokumentacija v angleščini