Replace plain text env var editor with structured EnvVarEditor
supporting plain values and secret references with inline "Seal"
to convert a value to a managed secret. Add issue hide action via
popover menu on issue detail. Adapters now emit envBindings with
typed plain/secret_ref entries instead of raw KEY=VALUE strings.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
