Make loading malformed skills fail-open (#8243)

Instead of failing to start Codex, clearly call out that N skills did
not load and provide warnings so that the user may fix them.

<img width="3548" height="874" alt="image"
src="https://github.com/user-attachments/assets/6ce041b2-1373-4007-a6dd-0194e58fafe4"
/>

codex-rs/tui2/src/lib.rs

@@ -68,7 +68,6 @@ mod resume_picker;
 mod selection_list;
 mod session_log;
 mod shimmer;
-mod skill_error_prompt;
 mod slash_command;
 mod status;
 mod status_indicator_widget;