perf: throttle OG image generation — nice 19 + 50ms sleep between renders

scripts/generate_og_images.py

@@ -13,6 +13,7 @@ from __future__ import annotations
 import argparse
 import json
 import sys
+import time
 from pathlib import Path
 
 
@@ -58,6 +59,7 @@ def generate_all(data_dir: Path, www_root: Path) -> None:
                 out_path.write_bytes(png)
                 generated += 1
                 u_gen     += 1
+                time.sleep(0.05)
             except Exception as exc:
                 errors += 1
                 u_err  += 1