Hide numeric prefixes on disabled TUI list rows (#15660)

- Remove numeric prefixes for disabled rows in shared list rendering.
These numbers are shortcuts, Ex: Pressing "2" selects option `#2`.
Disabled items can not be selected, so keeping numbers on these items is
misleading.
- Apply the same behavior in both tui and tui_app_server.
- Update affected snapshots for apps/plugins loading and plugin detail
rows.

_**This is a global change.**_

Before:
<img width="1680" height="488" alt="image"
src="https://github.com/user-attachments/assets/4bcf94ad-285f-48d3-a235-a85b58ee58e2"
/>

After:
<img width="1706" height="484" alt="image"
src="https://github.com/user-attachments/assets/76bb6107-a562-42fe-ae94-29440447ca77"
/>

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

@@ -5,4 +5,4 @@ expression: before
   Apps
   Loading installed and available apps...
 
-› 1. Loading apps...  This updates when the full list is ready.
+›    Loading apps...  This updates when the full list is ready.

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

@@ -9,8 +9,8 @@ expression: popup
 
 › 1. Back to plugins  Return to the plugin list.
   2. Install plugin   Install this plugin now.
-  3. Skills           design-review, extract-copy
-  4. Apps             Figma, Slack
-  5. MCP Servers      figma-mcp, docs-mcp
+     Skills           design-review, extract-copy
+     Apps             Figma, Slack
+     MCP Servers      figma-mcp, docs-mcp
 
   Press esc to close.

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

@@ -6,4 +6,4 @@ expression: popup
   Loading available plugins...
   This first pass shows the ChatGPT marketplace only.
 
-› 1. Loading plugins...  This updates when the marketplace list is ready.
+›    Loading plugins...  This updates when the marketplace list is ready.

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

@@ -7,7 +7,7 @@ expression: popup
 
   1. System default                                Use your operating system
                                                    default device.
-› 2. Unavailable: Studio Mic (current) (disabled)  Configured device is not
+›    Unavailable: Studio Mic (current) (disabled)  Configured device is not
                                                    currently available.
                                                    (disabled: Reconnect the
                                                    device or choose another