chore(release): prepare v1.26.0

[bmscomp]

Release prep for v1.26.0: image and kates-tester pins, chart versions and version tables.

• kates chart 0.11.2 → 0.11.3, appVersion and image tags 1.26.0, with a change entry naming the backend PRs since 1.25.1 (fix(native): the native image registers the API keys file's YAML model for reflection, so it starts with a named keys file #371, fix(chaos): orphan recovery undoes every fault left from before the Kates API started, and NetworkPolicies in any namespace #374–fix(security): the audit and pentest read each listener's protocol, so Kafka's default GSSAPI and named listeners no longer pass #379, fix(tune): no command or endpoint ranks tuning steps that no run measured: the tuning report is gone #386, fix(cluster): the health check reports a KRaft quorum it cannot describe instead of dropping it #403).
• Strimzi charts: strimzi-operator 0.3.5, kafka-cluster 1.0.9, connect-cluster 2.1.7 and mirror-maker2 0.11.5, all pinning kates-tester:1.26.0. Nothing under tester/ changed since 1.25.1.
• Other pins: the 12 Litmus experiment pins, kates/k8s/deployment.yaml, the registry docs (with the JVM tag the last release missed), the runbook, the README chart table and appendix D.

Local checks: scripts/check-versions.sh, gen-chart-table.sh --check and gen-version-matrix.sh --check pass, and helm lint passes on kates and strimzi-operator.

After merge, tag v1.26.0 on the merge commit to start the Release workflow. It builds the CLI, the kates JVM and native images, kates-tester and Connect, then the GitHub Release and the Homebrew tap.