Allow right-click “Save Device” in Devices panel with config scope selection and credential prompt

Implement a feature where users can right-click an existing device in the Devices panel and choose a "Save Device" option.

Expected behavior:

• User right-clicks any device in the Devices panel and selects "Save Device".
• Prompt the user for where to save the device configuration (user, folder, workspace scope).
• Confirm and collect any non-saved properties (e.g., password, nickname, etc.), pre-filling any known values if appropriate.
• Writes the selected device's structure to the correct brightscript.devices config in the chosen scope, following the config scheme and merging/deduplication logic as specified in Issue #690.

Requirements:

• Respects scope priority and merging rules described in #690
• Prompt for all required fields if not already saved (minimally: host, optionally: password, name, deviceId, etc)
• Write valid configuration entry for the device under the chosen scope
• Ensure no duplicate entries in the merged config
• Device should appear in the device list immediately after saving

Acceptance Criteria:

• Devices can be saved via right-click context menu
• Users are prompted for scope and additional info
• Config merging/deduplication works per #690

Reference for merging rules: #690