feat(dashboard): show build git SHA in header + profile page

The version label now renders 'v0.5.86 (<shortsha>)' when the flake build
injects NEXT_PUBLIC_GIT_SHA (git commit identity of the deployed artifact),
so any running dashboard traces to its exact source commit. Falls back to
semver-only when the env var is absent (local dev). Also fixes the profile
page repo link back to asepharyana/9router (MIBP merge target), replacing
the mhiqrambg fork label left over from the merge.

flake.nix

@@ -60,6 +60,9 @@
             bun install 2>&1
 
             echo "=== bun run build (next build --webpack) ==="
+            # Inline the git SHA into the client bundle so the dashboard header
+            # shows "v0.5.86 (<shortsha>)" — traceable build identity in the UI.
+            export NEXT_PUBLIC_GIT_SHA="${rev}"
             bun run build 2>&1
 
             echo "=== Build complete ==="