fix: use shutil.which to find uv in _trigger_rebuild; never 500 on rebuild failure

bincio/serve/server.py

@@ -11,6 +11,7 @@ from __future__ import annotations
 import json
 import re
 import secrets
+import shutil
 import subprocess
 import time
 from pathlib import Path
@@ -168,14 +169,18 @@ def _trigger_rebuild(handle: str) -> None:
         return
     if not _VALID_HANDLE.match(handle):
         return  # safety: never pass untrusted strings to subprocess
+    uv = shutil.which("uv") or str(Path.home() / ".local" / "bin" / "uv")
+    try:
         subprocess.Popen(
-        ["uv", "run", "bincio", "render",
+            [uv, "run", "bincio", "render",
              "--data-dir", str(data_dir),
              "--site-dir", str(site_dir),
              "--handle", handle],
             stdout=subprocess.DEVNULL,
             stderr=subprocess.DEVNULL,
         )
+    except Exception:
+        pass  # rebuild failure must never 500 the calling endpoint
 
 
 # ── Auth endpoints ────────────────────────────────────────────────────────────