fix: replace ripgrep with POSIX find/grep for CI compatibility

The translation parity script used 'rg', which isn't available
on the default ubuntu-latest runner. Swap it out for plain
find + grep so the docs-check workflow passes without installing
extra dependencies.

No functional change — same report, wider compatibility.

scripts/translation_parity_report.sh

@@ -19,8 +19,8 @@ fi
 tmp_dir="$(mktemp -d)"
 trap 'rm -rf "$tmp_dir"' EXIT
 
-(cd docs/en && rg --files -g '*.md' | sort) >"$tmp_dir/en_files.txt"
-(cd docs/cs && rg --files -g '*.md' | sort) >"$tmp_dir/cs_files.txt"
+(cd docs/en && find . -name '*.md' | sed 's|^\./||' | sort) >"$tmp_dir/en_files.txt"
+(cd docs/cs && find . -name '*.md' | sed 's|^\./||' | sort) >"$tmp_dir/cs_files.txt"
 
 comm -23 "$tmp_dir/en_files.txt" "$tmp_dir/cs_files.txt" >"$tmp_dir/missing_in_cs.txt"
 comm -13 "$tmp_dir/en_files.txt" "$tmp_dir/cs_files.txt" >"$tmp_dir/extra_in_cs.txt"
@@ -31,7 +31,7 @@ extra_count="$(wc -l <"$tmp_dir/extra_in_cs.txt" | tr -d ' ')"
 
 # Report any TODO markers in Czech files.
 todo_count="$(
-  (rg -n '\bTODO\b' docs/cs --glob '*.md' --glob '!README.md' || true) | wc -l | tr -d ' '
+  (find docs/cs -name '*.md' ! -name 'README.md' -exec grep -Hn '\bTODO\b' {} + || true) | wc -l | tr -d ' '
 )"
 
 echo "# Translation Parity Report (docs/en -> docs/cs)"