[Feature Request] Improve save workflow and keyboard shortcuts

[iamkartiknayak]

Issue/Description:
The current save dropdown in COSMIC Screenshot includes “Save to Clipboard” as an option. Unlike current impl image should be saved to clipboard at all times when a screenshot is taken, even when saving the image is selected.

Proposed changes:

• Remove “Save to Clipboard” from the dropdown
• Save screenshot to clipboard in all conditions
• Keep the dropdown focused only on save destinations:
  • Save to Pictures
  • Save to Custom Directory (opens a directory selection dialog)

Keyboard-driven workflow:

• Enter → always save the screenshot to clipboard
• Ctrl + Enter → save the screenshot to the currently selected save directory

This would make clipboard saving fast and consistent, while still allowing explicit control over file-based saving.

Additionally, introduce a dedicated button or menu entry to display all keyboard shortcuts associated with COSMIC Screenshot. This will scale well as future features are added (annotation, redaction, OCR, etc.), allowing users to quickly switch modes using known shortcuts that can always be referenced from within the app.

Expected Behavior:

• Dropdown only lists file-based save destinations
• Enter consistently saves to clipboard
• Ctrl + Enter saves to the selected directory
• A visible shortcut reference is available within the Screenshot UI

Other Notes:
This improves speed for common workflows, reduces UI clutter, and prepares the app for future feature expansion without increasing cognitive load.