[Feat] Add GLM 5.3 support to Z AI and OpenCode Go (#1244)

* feat(providers): add GLM 5.3 support

* feat(providers): enable GLM 5.3 for Z AI coding plans

* test(webview): cover Z AI model selection

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Co-authored-by: @taltas <6816042+taltas@users.noreply.github.com>