v1.45.2: hardening from the v1.45.1 review — R4-1, R4-2

R4-1: collecting superseded plan files runs after the configuration is already
durable, but an error listing the directory propagated out of config/set. The
client saw a failure for a revision the server had committed, and its retry
came back as a conflict. collect_plans now reports 0 instead of raising, and
config/set logs and proceeds — the event fires, the revision is returned.

R4-2: the pending set was cleared when a batch went out, not when it came back,
so every render during an in-flight content/sign queued another request: six
calls where one was needed, and unbounded on a socket that is slow rather than
busy. Queued and in-flight are separate states now; a failure backs off (2 s
doubling to 60 s) instead of retrying on the next frame; an in-flight entry
expires after 15 s so a promise that never settles cannot wedge retries; a late
answer after dispose() no longer renders.

Tests: test/signing.test.mjs — eight cases with hand-settled promises, verified
against a v1.45.1 checkout where four of them fail (2 sign calls instead of 1,
no backoff, a late answer rendering after teardown). Backend: a broken
collector still yields a successful save whose revision the next CAS accepts.
Pure collector: a disappearing directory returns 0.
Docs: CHANGELOG.md + CHANGELOG.ru.md + ARCHITECTURE.md + TESTING.md + STATUS.md.

docs/TESTING.md

@@ -234,6 +234,15 @@ 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]
+- [ ] Signing does not amplify on a bad connection (v1.45.2, review R4-2): with
+      the WebSocket slow or refusing, the card issues ONE sign request per url
+      and backs off after a failure instead of asking again on every render; a
+      request that never answers stops blocking retries after 15 s
+      [auto: unit: signing.test + smoke_space_card_bg]
+- [ ] A broken plans directory does not fail a save (v1.45.2, review R4-1): make
+      the plans folder unreadable and save the configuration — the save
+      succeeds, the revision is usable, and the next save does not conflict
+      [auto: backend test_a_failing_collector_does_not_undo_an_accepted_save]
 - [ ] Two editors, one plan (v1.45.1, review R3-1): with the same space open in
       two tabs, attach a background in each in turn — the plan last saved is the
       one served, and neither commit deletes the other's file. A rejected upload