TUI/Core: preserve duplicate skill/app mention selection across submit + resume (#10855)

## What changed

- In `codex-rs/core/src/skills/injection.rs`, we now honor explicit
`UserInput::Skill { name, path }` first, then fall back to text mentions
only when safe.
- In `codex-rs/tui/src/bottom_pane/chat_composer.rs`, mention selection
is now token-bound (selected mention is tied to the specific inserted
`$token`), and we snapshot bindings at submit time so selection is not
lost.
- In `codex-rs/tui/src/chatwidget.rs` and
`codex-rs/tui/src/bottom_pane/mod.rs`, submit/queue paths now consume
the submit-time mention snapshot (instead of rereading cleared composer
state).
- In `codex-rs/tui/src/mention_codec.rs` and
`codex-rs/tui/src/bottom_pane/chat_composer_history.rs`, history now
round-trips mention targets so resume restores the same selected
duplicate.
- In `codex-rs/tui/src/bottom_pane/skill_popup.rs` and
`codex-rs/tui/src/bottom_pane/chat_composer.rs`, duplicate labels are
normalized to `[Repo]` / `[App]`, app rows no longer show `Connected -`,
and description space is a bit wider.

<img width="550" height="163" alt="Screenshot 2026-02-05 at 9 56 56 PM"
src="https://github.com/user-attachments/assets/346a7eb2-a342-4a49-aec8-68dfec0c7d89"
/>
<img width="550" height="163" alt="Screenshot 2026-02-05 at 9 57 09 PM"
src="https://github.com/user-attachments/assets/5e04d9af-cccf-4932-98b3-c37183e445ed"
/>


## Before vs now

- Before: selecting a duplicate could still submit the default/repo
match, and resume could lose which duplicate was originally selected.
- Now: the exact selected target (skill path or app id) is preserved
through submit, queue/restore, and resume.

## Manual test

1. Build and run this branch locally:
   - `cd /Users/daniels/code/codex/codex-rs`
   - `cargo build -p codex-cli --bin codex`
   - `./target/debug/codex`
2. Open mention picker with `$` and pick a duplicate entry (not the
first one).
3. Confirm duplicate UI:
   - repo duplicate rows show `[Repo]`
   - app duplicate rows show `[App]`
   - app description does **not** start with `Connected -`
4. Submit the prompt, then press Up to restore draft and submit again.  
   Expected: it keeps the same selected duplicate target.
5. Use `/resume` to reopen the session and send again.  
Expected: restored mention still resolves to the same duplicate target.

codex-rs/core/tests/suite/live_reload.rs

@@ -101,7 +101,7 @@ async fn live_skills_reload_refreshes_skill_cache_after_skill_change() -> Result
         });
     let test = builder.build(&server).await?;
 
-    let skill_path = std::fs::canonicalize(test.codex_home_path().join("skills/demo/SKILL.md"))?;
+    let skill_path = dunce::canonicalize(test.codex_home_path().join("skills/demo/SKILL.md"))?;
 
     submit_skill_turn(&test, skill_path.clone(), "please use $demo").await?;
     let first_request = responses