Add learning hygiene CI guard

.gitea/scripts/hygiene-check.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+max_bytes=$((50 * 1024 * 1024))
+failed=0
+
+while IFS= read -r -d '' file; do
+  case "$file" in
+    .env|*/.env|*.DS_Store|*/node_modules/*|*.tmp|*.temp|*.bak|*.orig|*.rej|*.zip|*.tar|*.tar.gz|*.tgz|*.rar|*.7z)
+      echo "Forbidden tracked file: $file" >&2
+      failed=1
+      ;;
+  esac
+
+  if [ -f "$file" ]; then
+    size=$(wc -c < "$file")
+    if [ "$size" -gt "$max_bytes" ]; then
+      echo "Tracked file is larger than 50 MiB: $file ($size bytes)" >&2
+      failed=1
+    fi
+  fi
+done < <(git ls-files -z)
+
+exit "$failed"