fix v1.44.2: external review CR-1..CR-3

CR-1: the lock invariant is restated precisely (never by an accidental
tap; the door card's labeled button is the ONE sanctioned surface),
unlocking now confirms, and smoke_lock_invariant exercises all five
actuation paths (icon tap, controls[], card entities, _cardToggle,
opening card).

CR-2: attachment migration is transactional — the server COPIES files,
the config is committed with its revision check, and only then the old
folder is removed via the new houseplan/files/cleanup. A rejected save
no longer leaves the stored urls pointing at an emptied folder.

CR-3: migrate returns an exact {source: written} mapping; only confirmed
copies are rewritten, destination name collisions get a unique name
instead of silently linking a pre-existing file, and a failed migration
raises a toast instead of being swallowed.

+1 unit test (119), +1 backend test, +1 smoke (51 total); docs
same-commit

custom_components/houseplan/const.py

@@ -13,7 +13,7 @@ FILES_URL = "/houseplan_files/files"
 CONTENT_URL = "/api/houseplan/content"
 FILES_DIR = "houseplan/files"
 CONF_ADMIN_ONLY = "admin_only"
-VERSION = "1.44.1"
+VERSION = "1.44.2"
 
 DEFAULT_CONFIG: dict = {
     "spaces": [],