Fix backend patch: use middlewared's actual site-packages dir, add direct file patching

site.getsitepackages()[0] returns /usr/local/lib/python3.11/dist-packages/ on
TrueNAS 25.x but middlewared lives in /usr/lib/python3/dist-packages/.
sitecustomize.py was installed to the wrong directory and Python never loaded it.

Fix: derive SITE_PKG from middlewared.__file__ so the overlay and sitecustomize.py
land in the correct directory.

Also add direct patching of b2.py and restic.py in the overlay as the primary
backend approach — more reliable than an import hook since it works regardless
of Python's site initialisation configuration. apply.sh now also writes
hook_status.json at boot time so 'verify' shows OK without requiring a backup run.

Also fixes incorrect middlewared log path in README (/var/log/middlewared/middlewared.log
→ /var/log/middlewared.log) and simplifies the verify troubleshooting note.

uninstall.sh

@@ -67,7 +67,15 @@ if ! "$PYTHON" -c "import middlewared" 2>/dev/null; then
     fi
 fi
 
-SITE_PKG=$("$PYTHON" -c "import site; print(site.getsitepackages()[0])" 2>/dev/null || true)
+SITE_PKG=$("$PYTHON" -c "
+import os
+try:
+    import middlewared
+    print(os.path.dirname(os.path.dirname(os.path.abspath(middlewared.__file__))))
+except ImportError:
+    import site
+    print(site.getsitepackages()[0])
+" 2>/dev/null || true)
 
 if [ -n "$SITE_PKG" ] && [ -f "$SITE_PKG/sitecustomize.py" ]; then
     if grep -q "truecloud-patch" "$SITE_PKG/sitecustomize.py" 2>/dev/null; then