feat: age-based GC for temp images

save_tensor_png now reaps img_*.png files older than COMFY_BRIDGE_TMP_TTL
(env, default 3600s) after each write, so .comfy_bridge_tmp/ no longer
grows forever. Robust to races (ignores FileNotFoundError/OSError) and
never deletes the file just written.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/bridge/images.py

@@ -1,10 +1,27 @@
+import glob
 import os
+import time
 import uuid
 import numpy as np
 import torch
 from PIL import Image
 
 
+def _reap_old(out_dir: str, keep: str) -> None:
+    """Delete img_*.png in out_dir older than COMFY_BRIDGE_TMP_TTL (default
+    3600s) so the temp dir doesn't grow forever. Never touches `keep`."""
+    ttl = float(os.environ.get("COMFY_BRIDGE_TMP_TTL", "3600"))
+    cutoff = time.time() - ttl
+    for f in glob.glob(os.path.join(out_dir, "img_*.png")):
+        if f == keep:
+            continue
+        try:
+            if os.path.getmtime(f) < cutoff:
+                os.unlink(f)
+        except (FileNotFoundError, OSError):
+            pass  # races / permission churn -> best-effort
+
+
 def save_tensor_png(tensor: torch.Tensor, out_dir: str) -> str:
     """ComfyUI IMAGE [B,H,W,C] float 0..1 -> PNG file, returns path."""
     os.makedirs(out_dir, exist_ok=True)
@@ -14,6 +31,7 @@ def save_tensor_png(tensor: torch.Tensor, out_dir: str) -> str:
     img = Image.fromarray(arr, mode="RGB")
     path = os.path.join(out_dir, f"img_{uuid.uuid4().hex}.png")
     img.save(path)
+    _reap_old(out_dir, keep=path)
     return path