release: 2.5.4: audit stage 4 - panel behaviour

Cut without asking, as the owner said on 2026-10-15.

Signing in costs the same for an unknown name (M8) and ends the session the
browser presented (L16); the Account password check has its own limit
(L15). The HTTP server bounds the request, the answer and idle connections;
the full backup moves its own deadline (L14). Monitoring refreshes are
scheduled from htmx:afterRequest with a back-off and a 30 s timeout, and a
lost session sends htmx to sign-in (M11). The Outbound log clamps its page
(L10) and filters by status and day; the multiplier refuses NaN (L11); a
rate-limited refusal is red (L18); Recalculate asks before it drops an
unsaved edit (L19); Reload configuration writes what a restore writes and
removes the keys of deleted domains (L13, L17). The cards layout orders by
number. A notification is owed to each recipient (migration 0011). A DNS
outage is unknown, each resolver with its own time (M14, M15). DMARC
reports too large are refused for their size. An inbound upstream has one
TLS mode, changed for all its domains (L5). Plus the findings of both
reviews (eaa7de0). Commits 07be0cf, 643892a, ca876c1, 80e3979, 2b8e0c0,
b90a2f0, eee089a, 006bed7, 32dfe4a, eaa7de0.

Rolled out to the test server as 2.5.3-post.eaa7de0 (the same code):
migration 0011 applied, schema 11; all programs RUNNING, the container
healthy. Resync's key cleanup checked against the live data: every key
directory is a domain's or the hostname's, nothing to remove.

CHANGELOG cut; pin 2.5.4 in deploy/docker-compose.yml, README, guide (and
its sample restore message); development.md "from pin" and the stage's row;
roadmap row and recommended order; stage 4 marked shipped in the plan. No
tag.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/guide.md

@@ -190,14 +190,14 @@ cat ./data/setup-token
 #### Fixed image tag
 
 `deploy/docker-compose.yml` pins an explicit version (`ghcr.io/mixeme/selfpost:X.Y.Z`),
-deliberately never `:latest`. The current pin is `2.5.3`. **No 2.x image is
+deliberately never `:latest`. The current pin is `2.5.4`. **No 2.x image is
 published on ghcr.io yet** (the newest there is `1.3.0`); until one is, build
 it from the checkout under the pinned name, and Compose uses the local image
 instead of pulling:
 
 ```sh
-docker build -f build/Dockerfile --build-arg VERSION=2.5.3 \
-  -t ghcr.io/mixeme/selfpost:2.5.3 .
+docker build -f build/Dockerfile --build-arg VERSION=2.5.4 \
+  -t ghcr.io/mixeme/selfpost:2.5.4 .
 ```
 
 `VERSION` must equal the tag: it is the version the backup check compares
@@ -861,7 +861,7 @@ A version mismatch at step 5 refuses to start and leaves `/data` untouched —
 the panel exits with a message naming the tag to use, e.g.:
 
 ```
-backup: this backup was created by SelfPost 2.5.2 but this image is 2.5.3 — restore into the matching image (selfpost:2.5.2)
+backup: this backup was created by SelfPost 2.5.3 but this image is 2.5.4 — restore into the matching image (selfpost:2.5.3)
 ```
 
 Fix the tag in `docker-compose.yml` (build that tag as under [Fixed image