agent-platform release v4.59.0

components.klaus-gateway.versionRange admits the 2.x line (>=1.20.0 <3.0.0) (giantswarm/klaus-gateway#319). klaus-gateway 2.0.0 is the Slack-only gateway: the web and CLI channels, the OpenAI-compatible /v1 front door and the Klaus instance path are removed there; the values keys this chart still forwards for them (cli, lifecycle, upstream, agentgateway, routing.defaultTTL, a2a.saToken) are accepted by the 2.x chart as no-ops, so the installations roll to it unchanged. Those keys leave this chart in a later change, once the 2.x line has rolled.