Publish v0.26.1-rc.1

# Description Publish release v0.26.1-rc.1 before code freeze. This includes security patches (Go bump to 1.25.9) and fixing QA-reported issue #2303. Release must include: - Turtles release. - Turtles Providers release. - Update to `rancher/charts` and `rancher/rancher`. This will be the final RC for QA validation before the sign-off date (April 23rd).