Fix four quality findings from re-review

sitecustomize.py: exec_module now records a FAIL status when the underlying
module load raises, instead of leaving hook_status.json unwritten. cmd_verify
will now show a diagnostic FAIL rather than the misleading "no status file".

sitecustomize.py: URL-fix loop covers --repository and --repository= in
addition to --repo/--repo=/-r; these are documented restic synonyms.

sitecustomize.py: _replace fallback now catches AttributeError in addition
to TypeError so an unrecognised ResticConfig return type silently falls back
to returning the unmodified result rather than crashing the backup job.

patch_ui.py: warns when FIND.subn produces a count other than 1, making
unexpected multi-replacement visible in the apply log.

uninstall.sh: find for JS bundle restore now includes /usr/share/truenas-ui,
matching all three entries in patch_ui.py's WEBUI_CANDIDATES.

patch/patch_ui.py

@@ -93,6 +93,12 @@ def main():
         shutil.copy2(path, backup)
 
     patched, count = FIND.subn(REPLACE, content)
+    if count != 1:
+        print(
+            f"[truecloud-patch] WARNING: {count} replacement(s) in {path}; "
+            f"expected exactly 1 — file an issue at "
+            f"https://github.com/sudolulo/truenas-truecloud-patch"
+        )
 
     tmp = path + ".tmp"
     try: