fix(tray): resolve icons advertised with custom theme path

[pedroboussiengui]

Problem

Tray icons from apps that ship their own icon theme (Dropbox, KeePassXC, and others) never render — only the missing-icon fallback shows up. The bar still receives the item (clicks and the menu work), but the pixmap is blank.

Root cause

Such apps expose their icon over StatusNotifierItem as:

image://icon/<name>?path=/absolute/theme/root

For example, Dropbox sends:

image://icon/dropboxstatus-idle?path=/home/<user>/.dropbox-dist/dropbox-lnx.x86_64-XXXXXXX/images

The advertised path is the theme root (containing hicolor/<size>/<category>/...), not the leaf directory of the file. The previous Icons.getTrayIcon split the URL and built file://<path>/<name> directly — no extension, wrong directory — so IconImage could never load it.

Fix

• Replace getTrayIcon with getTrayIconCandidates(id, icon) which returns an ordered list of candidate URLs:
  1. iconSubs overrides (unchanged behavior).
  2. The raw path root, with .png / .svg.
  3. Standard freedesktop layout under the path: [hicolor|""]/<size>/<category>/<name>.<ext> across common sizes (16x16 → scalable) and categories (status, apps, actions, …).
• TrayItem consumes the list and walks to the next candidate on Image.Error, stopping at the first that loads.

For icons without ?path= (most apps using the system theme, or image://qspixmap/... from IconPixmap), the candidate list is just [icon], so behavior is unchanged.

Files

• utils/Icons.qml: introduces getTrayIconCandidates.
• modules/bar/components/TrayItem.qml: iterates candidates on load failure.

Testing

• Dropbox 252.4.3485 on Hyprland: tray icon now renders correctly (resolves to …/images/hicolor/16x16/status/dropboxstatus-idle.png).
• Regular apps using image://icon/<name> (Arch-Update, etc.): unchanged.
• image://qspixmap/... from apps that embed pixmaps via D-Bus: unchanged.
• iconSubs substitutions in bar.tray.iconSubs: still applied first.

Notes

The freedesktop spec calls for a full theme lookup using index.theme, but doing that in pure QML would mean parsing the theme file and walking directories. The candidate-list approach covers every real-world layout I could find (Dropbox, KeePassXC, Discord-style trays) with negligible cost — IconImage only requests the next URL when the previous one errors.