v1.45.0: external review of v1.44.8 — R2-1, R2-2, R2-3

R2-1 (high): plan replacement committed filesystem state before the config CAS.
The upload wrote the final name and unlinked the other extension, so a rejected
config write left the live plan already replaced — or the stored config
pointing at a deleted file. Uploads now go to <space>.<token>.<ext> and delete
nothing; houseplan/plan/cleanup runs only after the config write is accepted.
The '.' separator is load-bearing: a space id cannot contain one, so cleaning
'f1' can never reach the files of 'f1-attic'.

R2-2: the backend signs at most MAX_SIGN_PATHS (200) per request and ignores
the rest silently, while the card sent its whole cache in one call and trusted
any cached entry forever — past 200 attachments the later ones stopped being
refreshed and expired for good. Requests are chunked to the shared constant,
entries carry their issue time (aging urls keep rendering while a replacement
is fetched, expired ones are dropped), and the cache is pruned to urls the live
config still references.

R2-3: areaClimate() rescanned the whole registry per room and per measurement.
areaClimateMap() classifies once and returns Map<area,{temp,hum}>, memoized on
hass identity so fresh states are always observed. Smoke measurement: 133
registry scans per update with 44 rooms before, 2 after, flat in room count.

Also: smoke_ux_fixes wrote its screenshot to a hard-coded /tmp path and could
not run on Windows.

Tests: smoke_plan_upload_reject, smoke_sign_cap, smoke_climate_once (all fail
on v1.44.8), three backend tests for versioned plan names and cleanup scoping,
unit tests for chunk/referencedContentUrls and areaClimateMap.
Docs: CHANGELOG.md + CHANGELOG.ru.md + ARCHITECTURE.md + TESTING.md + STATUS.md.

docs/TESTING.md

@@ -234,6 +234,20 @@ Run the *core flows* (marked ★ below) in each environment at least once per mi
       are only reachable through /api/houseplan/content/… with a session; the
       old /houseplan_files/plans|files paths return 404 after a restart; old
       stored URLs keep working (rewritten on read) [auto+manual]
+- [ ] Rejected save leaves the plan intact (v1.45.0, review R2-1): attach a new
+      background, make the config write fail (a second tab saving first is
+      enough) — the previously stored plan is still served, with the same or a
+      different extension; after a successful save the old files are gone
+      [auto: smoke_plan_upload_reject + backend test_plan_upload_does_not_touch_the_previous_file]
+- [ ] Signature cache on a wall tablet (v1.45.0, review R2-2): with more than
+      200 signed urls every one of them is refreshed (batched), entries for
+      files no longer in the config are dropped, an expired signature is never
+      served and an aging one keeps working while its replacement arrives
+      [auto: smoke_sign_cap]
+- [ ] Climate cost does not grow with rooms (v1.45.0, review R2-3): on a plan
+      with dozens of rooms an unrelated HA state update triggers ONE registry
+      pass, repeated renders on the same snapshot trigger none, and a changed
+      sensor value is still visible immediately [auto: smoke_climate_once]
 - [ ] Plan upload survives a concurrent config revision (v1.44.8): with a second
       tab open on the same plan, attach a background image in space settings —
       the plan shows immediately, `plan_url` is in `.storage/houseplan.config`,