feat: git SHA version badge in admin, fix finanzplan caching, drop gitea remote

- AdminShell: shows NEXT_PUBLIC_GIT_SHA in sidebar footer
- Dockerfile + build-pitch-deck.yml: pass --build-arg GIT_SHA at build time
- FinanzplanSlide: fetch with cache:no-store to always show current DB values
- finanzplan routes: Cache-Control: no-store to prevent CDN/proxy staling
- CLAUDE.md: remove dead gitea remote (only origin exists)

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

.gitea/workflows/build-pitch-deck.yml

@@ -35,6 +35,7 @@ jobs:
           cd pitch-deck
           SHORT_SHA=$(git rev-parse --short HEAD)
           docker build \
+            --build-arg GIT_SHA=${SHORT_SHA} \
             -t registry.meghsakha.com/breakpilot/pitch-deck:latest \
             -t registry.meghsakha.com/breakpilot/pitch-deck:${SHORT_SHA} \
             .