Fix macOS tray icon visibility on light menu bars

[gupsammy]

Summary

• Invert macOS tray icon PNGs from white to black and mark them as template images so macOS automatically adapts their color for light/dark menu bars
• Add set_tray_template_icon helper that re-applies the template flag after every set_icon call (needed because the upstream tray-icon crate resets it)
• Add .icon_as_template(cfg!(target_os = "macos")) to TrayIconBuilder for the initial icon
• Windows behavior is unchanged (tray-default-icon.png untouched, template logic gated behind #[cfg(target_os = "macos")])

Test plan

• Build the desktop app on macOS
• Switch macOS appearance to Light (System Settings > Appearance > Light) and verify tray icon is visible (black)
• Switch to Dark appearance and verify tray icon is visible (white)
• Switch recording modes (Studio, Instant, Screenshot) and verify each icon adapts
• Start a recording and verify the stop icon also adapts
• Verify Windows build is unaffected (no template logic compiled in)

[greptile-apps]

_{5 files reviewed, 1 comment}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

.icon_as_template(true) is now unconditional. The previous code used cfg!(target_os = "macos") to conditionally apply this only on macOS. While this doesn't cause runtime issues (the method exists on all platforms), using an unconditional true is slightly less clear than the previous version. Consider keeping the cfg! macro for clarity.

Previous:

Suggested change

	.icon_as_template(true)
	.icon_as_template(cfg!(target_os = "macos"))

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

Prompt To Fix With AI

This is a comment left during a code review.
Path: apps/desktop/src-tauri/src/tray.rs
Line: 669:669

Comment:
`.icon_as_template(true)` is now unconditional. The previous code used `cfg!(target_os = "macos")` to conditionally apply this only on macOS. While this doesn't cause runtime issues (the method exists on all platforms), using an unconditional `true` is slightly less clear than the previous version. Consider keeping the `cfg!` macro for clarity.

Previous:
```suggestion
        .icon_as_template(cfg!(target_os = "macos"))
```

<sub>Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!</sub>

How can I resolve this? If you propose a fix, please make it concise.