feat: Add marketplace source filtering and plugin share context (#21419)

Adds marketplaceKinds to plugin/list for local, workspace-directory, and
shared-with-me; omitted params keep default local plus gated global
behavior, while explicit kinds are exact.

Exposes shareContext on plugin summaries from local share mappings and
remote workspace/shared responses, including remotePluginId and nullable
creator metadata.

Adds shared-with-me listing through /ps/plugins/workspace/shared,
renames the workspace remote namespace to workspace-directory, and keeps
direct remote read/share/install/update/delete paths gated by plugins
rather than remote_plugin.

codex-rs/tui/src/chatwidget/tests/helpers.rs

@@ -1439,6 +1439,7 @@ pub(super) fn plugins_test_summary(
     PluginSummary {
         id: id.to_string(),
         name: name.to_string(),
+        share_context: None,
         source: PluginSource::Local {
             path: plugins_test_absolute_path(&format!("plugins/{name}")),
         },