Record the Faktiskā blank-temperature fix and correct a runbook bug

Documents release a6b2b84 (the queryLatestTemperatures fix and the user's
CSS polish pass) in the changelog and README status line. Also fixes a real
bug in VPS_RELEASE_RUNBOOK.md's own checksum step, found by actually running
it for this release: it generated the .sha256 file against a full local
path rather than a bare filename, which fails verification on the VPS since
that path doesn't exist there.

docs/VPS_RELEASE_RUNBOOK.md

@@ -74,15 +74,20 @@ with the new commit.
 
 ```bash
 mkdir -p /tmp/weathertool-release
-OUT=/tmp/weathertool-release/weathertool-$SHA.tar.gz
-docker save weathertool:$SHA | gzip > "$OUT"
-sha256sum "$OUT" | tee "$OUT.sha256"
+cd /tmp/weathertool-release
+docker save weathertool:$SHA | gzip > weathertool-$SHA.tar.gz
+sha256sum weathertool-$SHA.tar.gz | tee weathertool-$SHA.tar.gz.sha256
 ```
 
+Generate the checksum from a bare filename (after `cd`-ing into the
+directory), not a full path — `sha256sum -c` on the VPS checks the exact
+path string recorded in the `.sha256` file, and a local absolute path won't
+exist there. (Found by running this step for real, not a hypothetical.)
+
 ## 4. Transfer to the VPS and verify
 
 ```bash
-scp "$OUT" "$OUT.sha256" vps:/tmp/
+scp weathertool-$SHA.tar.gz weathertool-$SHA.tar.gz.sha256 vps:/tmp/
 
 ssh vps "cd /tmp && sha256sum -c weathertool-$SHA.tar.gz.sha256"
 # must print: weathertool-<SHA>.tar.gz: OK