[codex] Support npm marketplace plugin sources (#29375)

## Why

Marketplace source deserialization treated `{"source":"npm", ...}` as
unsupported. The loader logged and skipped the entry, so npm-backed
plugins never appeared in `plugin list --available` and `plugin add`
returned "plugin not found".

Codex plugins are installed from a plugin root, not from an npm
dependency tree. For npm-backed marketplace entries, Codex should fetch
the published package contents without running package scripts or
installing unrelated dependencies.

## What changed

- Add `npm` marketplace plugin sources with `package`, optional semver
`version` or version range, and optional HTTPS `registry`.
- Reject unsafe npm source fields before materialization, including
invalid package names, non-semver version selectors, plaintext or
credential-bearing registry URLs, and registry query/fragment data.
- Materialize npm plugins with `npm pack --ignore-scripts`, then unpack
the resulting tarball through the existing hardened plugin bundle
extractor.
- Enforce npm archive and extracted-size limits, require the standard
npm `package/` archive root, and verify the extracted `package.json`
name matches the requested package before installing.
- Keep plugin listings, install-source descriptions, CLI JSON/human
output, app-server v2 `PluginSource`, TUI source summaries, regenerated
schema fixtures, and app-server documentation in sync.

## Impact

Marketplaces can distribute Codex plugins from public or configured
private HTTPS npm registries using the same install flow as existing
materialized plugin sources. `npm` must be available on `PATH` when an
npm-backed plugin is installed.

Fixes #27831

## Validation

- `just write-app-server-schema`
- `just test -p codex-core-plugins -p codex-app-server-protocol -p
codex-app-server -p codex-cli`
  - npm/schema/core-plugin coverage passed in the run.
- The full focused command finished with `1739 passed`, `11 failed`, and
`6 timed out`; the failures were unrelated local app-server environment
failures from `sandbox-exec: sandbox_apply: Operation not permitted`
plus one missing `test_stdio_server` helper binary.
- Installed an npm-published Codex plugin package through a throwaway
local marketplace and throwaway `CODEX_HOME` to exercise the real npm
materialization path end to end.

codex-rs/tui/src/chatwidget/plugin_catalog.rs

@@ -1474,6 +1474,12 @@ fn plugin_source_summary(plugin: &PluginDetail) -> String {
             Some(ref_name) => format!("Git · {url}@{ref_name}"),
             None => format!("Git · {url}"),
         },
+        PluginSource::Npm {
+            package, version, ..
+        } => match version {
+            Some(version) => format!("npm · {package}@{version}"),
+            None => format!("npm · {package}"),
+        },
         PluginSource::Remote => {
             let marketplace_label =
                 MarketplaceProduct::from_marketplace_name(&plugin.marketplace_name)

codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__plugin_detail_popup_npm_source.snap

@@ -0,0 +1,20 @@
+---
+source: tui/src/chatwidget/tests/popups_and_settings.rs
+expression: strip_osc8_for_snapshot(&popup)
+---
+  Plugins
+  Figma · Can be installed · ChatGPT Marketplace
+  Data shared with this app is subject to the app's terms of service and privacy policy. Learn
+  more.
+  Turn Figma files into implementation context.
+
+› 1. Back to plugins  Return to the plugin list.
+  2. Install plugin   Install this plugin now.
+     Source           npm · @acme/figma-plugin@^1.2.0
+     Auth             Auth on install
+     Skills           design-review, extract-copy
+     Hooks            PreToolUse (1), Stop (2)
+     Apps             Figma, Slack
+     MCP Servers      figma-mcp, docs-mcp
+
+  Press esc to close.

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

@@ -664,6 +664,51 @@ async fn plugin_detail_popup_snapshot_labels_personal_marketplace_as_local() {
     );
 }
 
+#[tokio::test]
+async fn plugin_detail_popup_snapshot_shows_npm_source() {
+    let (mut chat, _rx, _op_rx) = make_chatwidget_manual(/*model_override*/ None).await;
+    chat.set_feature_enabled(Feature::Plugins, /*enabled*/ true);
+
+    let mut summary = plugins_test_summary(
+        "plugin-figma",
+        "figma",
+        Some("Figma"),
+        Some("Design handoff."),
+        /*installed*/ false,
+        /*enabled*/ true,
+        PluginInstallPolicy::Available,
+    );
+    summary.source = PluginSource::Npm {
+        package: "@acme/figma-plugin".to_string(),
+        version: Some("^1.2.0".to_string()),
+        registry: Some("https://npm.example.com".to_string()),
+    };
+    let response = plugins_test_response(vec![plugins_test_curated_marketplace(vec![
+        summary.clone(),
+    ])]);
+    let cwd = chat.config.cwd.clone();
+    chat.on_plugins_loaded(cwd.to_path_buf(), Ok(response));
+    chat.add_plugins_output();
+    let plugin = plugins_test_detail(
+        summary,
+        Some("Turn Figma files into implementation context."),
+        &["design-review", "extract-copy"],
+        &[
+            (codex_app_server_protocol::HookEventName::PreToolUse, 1),
+            (codex_app_server_protocol::HookEventName::Stop, 2),
+        ],
+        &["Figma", "Slack"],
+        &["figma-mcp", "docs-mcp"],
+    );
+    chat.on_plugin_detail_loaded(cwd.to_path_buf(), Ok(PluginReadResponse { plugin }));
+
+    let popup = render_bottom_popup(&chat, /*width*/ 100);
+    assert_chatwidget_snapshot!(
+        "plugin_detail_popup_npm_source",
+        strip_osc8_for_snapshot(&popup)
+    );
+}
+
 #[tokio::test]
 async fn plugin_detail_popup_distinguishes_admin_installed_from_enabled() {
     let (mut chat, _rx, _op_rx) = make_chatwidget_manual(/*model_override*/ None).await;