fix(window): focus settings on first open

[LRainner]

Summary

• explicitly show and focus newly created auxiliary windows
• keep the existing asynchronous tray handler to avoid Windows deadlocks
• share the same display path for new and existing settings windows

Validation

• cargo fmt --check
• cargo check
• git diff --check

Summary by CodeRabbit

• Bug Fixes
  • Improved auxiliary window handling so existing windows are reliably shown and focused.
  • Ensured newly created and reused windows behave consistently.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 1e5c9f1a-99c4-4964-81d1-1996cc9adf0e

📥 Commits

Reviewing files that changed from the base of the PR and between 8436479 and 3e1b7a8.

📒 Files selected for processing (1)

• src-tauri/src/lib.rs

---

📝 Walkthrough

Walkthrough

Changes

Auxiliary window flow

Layer / File(s)	Summary
Resolve and display auxiliary window src-tauri/src/lib.rs	show_aux_window resolves an existing or newly built window, then consistently calls show() and set_focus() with errors mapped to String.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• LRainner/AgentCat#22: Updates auxiliary-window opening through show_window and settings dispatch to show_aux_window.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly reflects the main behavior change: focusing the settings window on first open.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

---

_{Comment @coderabbitai help to get the list of available commands.}