v1.46.4: detached plans were being collected as garbage — data loss

Deployed v1.46.3 to my own instance, restarted, and the startup sweep deleted
both floor plans: config/houseplan/plans/ went from f1.svg + f2.png to empty.
The backup is a SecureTar, so they are gone.

The rule was wrong, not the code. v1.46.0 introduced collection that treats
'nothing references this right now' as abandoned and gives it an hour. But
detaching a plan — switching a space to 'draw' — is a normal, reversible action,
and the editor's own comment says the file stays on disk. Those two plans had
been detached for weeks; every pass since v1.46.0 was entitled to remove them,
and the one that finally ran did.

New rule, one for every path:
  * superseded by a commit (was in the old revision, is not in the new) — goes
    immediately; that is the one thing a commit knows for certain;
  * belongs to a space or marker that still exists — never collected, at any
    age, because unreferenced is not abandoned;
  * a per-dialog staging folder (up_*) — one hour, unchanged: by construction it
    only ever holds an upload from a dialog that was never saved;
  * anything else — thirty days.

The  flag I added an hour ago is gone with it: two rules for the same
question is how this happened. Tests updated to the new grace, plus two that pin
the distinction directly.

I am sorry about the files.

custom_components/houseplan/const.py

@@ -22,9 +22,19 @@ MAX_SIGN_PATHS = 200
 # seconds ago may belong to another client's transaction that has not written
 # its configuration yet (review R3-1).
 PLAN_ORPHAN_TTL_S = 3600
+
+# The scheduled sweep is a different judgement from a commit's. A commit knows
+# it replaced a file; the timer only knows nobody points at one right now — and
+# "nobody points at it" is a normal, reversible state. Detaching a plan (switch
+# a space to "draw") leaves the image on disk on purpose, and re-attaching it
+# later is a thing people do. On 2026-07-28 the hourly rule applied to that case
+# and removed two plans the owner had detached weeks earlier; they were not
+# recoverable. So the timer waits a month, and never touches a plan or an
+# attachment that still belongs to something in the configuration.
+SCHEDULED_GRACE_S = 30 * 24 * 3600
 FILES_DIR = "houseplan/files"
 CONF_ADMIN_ONLY = "admin_only"
-VERSION = "1.46.3"
+VERSION = "1.46.4"
 
 DEFAULT_CONFIG: dict = {
     "spaces": [],