Fix kill switch not cleared on reinstall; guard midclt delete; tighten sitecustomize imports

install.sh: running install.sh after a recover.sh left /data/truecloud-patch/disabled
in place, so apply.sh silently skipped all patching and middlewared restarted
without the patch. Clear the kill switch file before running apply.sh.

uninstall.sh: midclt initshutdownscript.delete was unguarded under set -euo pipefail,
so a delete failure (already-removed entry, transient API error) aborted the script
before sitecustomize.py was cleaned up or /data/truecloud-patch/ was removed. Now
guarded with an if/else that warns and continues.

sitecustomize.py: move importlib.machinery/.util imports inside the if block in
find_spec so they only execute when intercepting our two target modules, not on
every module import across the whole process. In _install(), import os before
importlib.util so the kill switch check (cheap) runs before the importlib import
(slightly heavier on first use). Remove the unused orig variable in _patch_restic.

patch_ui.py: add explicit encoding="utf-8" to both open() calls. errors="replace"
on read so malformed bytes in a bundle don't silently skip a candidate file.

uninstall.sh

@@ -32,8 +32,11 @@ for s in json.load(sys.stdin):
 
 if [ -n "$IDS" ]; then
     for id in $IDS; do
-        midclt call initshutdownscript.delete "$id" > /dev/null
-        echo "  Removed initshutdownscript id=$id"
+        if midclt call initshutdownscript.delete "$id" > /dev/null; then
+            echo "  Removed initshutdownscript id=$id"
+        else
+            echo "  WARNING: could not delete id=$id (already gone?)"
+        fi
     done
 else
     echo "  No entry found (already removed or never installed)."