Extend runtime auth to account, plugin, and file requests (#59564)

## What changed

- Use the shared runtime and effective configuration for account API clients and remote plugin requests, including standalone plugin commands.
- Support dual-header and assertion-only authentication for remote plugins and MCP file uploads when runtime agent instances are enabled.
- Keep plugin credentials and caches scoped to the thread's account when resuming with different credentials. Bind request pools and multi-step plugin storage operations to the selected account so account replacement revokes stale operations.
- Protect runtime credentials on cross-origin redirects while preserving configured routing policies and legacy authentication for custom backends.
- Apply server-provided `upload_headers` to file storage uploads.

## Testing

Add coverage for shared runtime registration, both authentication modes, configuration reloads, resumed-thread account selection, account replacement during plugin uploads and downloads, and credential stripping on redirects. Extend file upload tests to verify runtime assertions and storage-only upload headers.

GitOrigin-RevId: 68aef81051a6f9bf919fffda52f372b108fce805

codex-rs/cli/src/plugin_cmd.rs

@@ -7,7 +7,7 @@ use codex_app_server_protocol::PluginAuthPolicy;
 use codex_app_server_protocol::PluginInstallPolicy;
 use codex_core::config::Config;
 use codex_core::config::find_codex_home;
-use codex_core::plugins_manager_for_config;
+use codex_core::plugins_manager_for_config_with_runtime;
 use codex_core_plugins::ConfiguredMarketplace;
 use codex_core_plugins::OPENAI_BUNDLED_MARKETPLACE_NAME;
 use codex_core_plugins::PluginInstallOutcome;
@@ -773,10 +773,9 @@ async fn load_plugin_command_context(
         .context("failed to load configuration")?;
     let plugins_input = config.plugins_config_input();
     let auth_manager = load_cli_auth_manager(&config).await?;
-    let manager = Arc::new(plugins_manager_for_config(
-        &config,
-        Arc::clone(&auth_manager),
-    ));
+    let manager = Arc::new(
+        plugins_manager_for_config_with_runtime(&config, Arc::clone(&auth_manager)).await?,
+    );
     Ok(PluginCommandContext {
         codex_home: codex_home.to_path_buf(),
         plugins_input,
@@ -861,7 +860,9 @@ async fn fetch_remote_marketplaces(
         );
         return Ok(RemoteMarketplaceListing::default());
     }
-    let service = context.plugins_input.remote_plugin_service_config();
+    let service = context
+        .manager
+        .remote_plugin_service_config(&context.plugins_input);
     let result = if context.plugins_input.remote_plugin_enabled {
         remote::fetch_remote_marketplaces(
             &service,