Fix three findings from final clean-pass audit

- apply.sh: gate sitecustomize.py install on backup success; a failed
  backup cp (disk full, read-only mount) previously fell through and
  overwrote the vendor file with no recovery path
- create_task.py: handle unexpected 2xx response schema in cmd_create;
  bare KeyError on result['id'] is replaced with a diagnostic print
- uninstall.sh: mv inside while loop had no error handling; under
  set -euo pipefail a failed mv aborted the script before rm -rf PATCH_DIR,
  leaving the system in partial-uninstall limbo

patch/apply.sh

@@ -85,19 +85,26 @@ if [ -z "$SITE_PKG" ]; then
     echo "  Run: $PYTHON -c \"import site; print(site.getsitepackages())\""
 else
     # Back up any pre-existing sitecustomize.py that isn't ours.
+    _can_install=true
     if [ -f "$SITE_PKG/sitecustomize.py" ] && \
        ! grep -q "truecloud-patch" "$SITE_PKG/sitecustomize.py" 2>/dev/null; then
-        cp "$SITE_PKG/sitecustomize.py" \
-           "$SITE_PKG/sitecustomize.py.pre-truecloud-patch"
+        if cp "$SITE_PKG/sitecustomize.py" \
+              "$SITE_PKG/sitecustomize.py.pre-truecloud-patch"; then
             echo "OK: Backed up existing sitecustomize.py"
+        else
+            echo "WARNING: Could not back up existing sitecustomize.py; skipping install to avoid data loss."
+            _can_install=false
+        fi
     fi
 
+    if $_can_install; then
         if cp "$PATCH_DIR/sitecustomize.py" "$SITE_PKG/sitecustomize.py" 2>/dev/null; then
             echo "OK: Installed sitecustomize.py → $SITE_PKG/sitecustomize.py"
         else
             echo "WARNING: Failed to write $SITE_PKG/sitecustomize.py (permission error?)"
         fi
     fi
+fi
 
 # ── Step 2: Angular bundle ────────────────────────────────────────────────────
 

patch/create_task.py

@@ -179,7 +179,10 @@ def cmd_create(client, args):
     }
 
     result = client("POST", "/cloud_backup", body)
+    try:
         print(f"Created task id={result['id']}  name={result['description']!r}")
+    except (KeyError, TypeError):
+        print(f"Task created but response schema was unexpected: {result}")
 
 
 # ── CLI ───────────────────────────────────────────────────────────────────────

uninstall.sh

@@ -104,9 +104,12 @@ echo "Restoring UI bundle backup ..."
 RESTORED=0
 while IFS= read -r backup; do
     original="${backup%.pre-truecloud-patch}"
-    mv "$backup" "$original"
+    if mv "$backup" "$original"; then
         echo "  Restored: $original"
         RESTORED=1
+    else
+        echo "  WARNING: Could not restore $original — backup left at $backup"
+    fi
 # Keep these paths in sync with WEBUI_CANDIDATES in patch/patch_ui.py
 done < <(find /usr/share/truenas /usr/share/truenas-ui /var/www/truenas \
               -name "*.js.pre-truecloud-patch" 2>/dev/null)