feat: Add workspace plugin sharing APIs (#20278)

1. Adds v2 plugin/share/save, plugin/share/list, and plugin/share/delete
RPCs.
2. Implements save by archiving a local plugin root, enforcing a size
limit, uploading through the workspace upload flow, and supporting
updates via remotePluginId.
3. Lists created workspace plugins
4. Deletes a previously uploaded/shared plugin.

codex-rs/app-server/tests/suite/v2/plugin_read.rs

@@ -139,7 +139,6 @@ async fn plugin_read_rejects_remote_marketplace_when_remote_plugin_is_disabled()
             .message
             .contains("remote plugin read is not enabled")
     );
-    assert!(err.error.message.contains("chatgpt-global"));
     Ok(())
 }
 
@@ -253,7 +252,7 @@ async fn plugin_read_reads_remote_plugin_details_when_remote_plugin_enabled() ->
     let request_id = mcp
         .send_plugin_read_request(PluginReadParams {
             marketplace_path: None,
-            remote_marketplace_name: Some("chatgpt-global".to_string()),
+            remote_marketplace_name: Some("caller-marketplace-is-ignored".to_string()),
             plugin_name: "plugins~Plugin_00000000000000000000000000000000".to_string(),
         })
         .await?;
@@ -413,11 +412,6 @@ async fn plugin_read_rejects_invalid_remote_plugin_name() -> Result<()> {
 
     assert_eq!(err.error.code, -32600);
     assert!(err.error.message.contains("invalid remote plugin id"));
-    assert!(
-        err.error
-            .message
-            .contains("only ASCII letters, digits, `_`, `-`, and `~` are allowed")
-    );
     Ok(())
 }