Add app dashboard screenshot to README

[Copilot]

Added visual documentation of the main app interface showing the professional dark theme, real-time charts, delta cards, intelligence report, and monitoring features.

Changes

• Embedded dashboard screenshot in Overview section of README
• Image sized to 300px width for optimal rendering
• Positioned immediately after app description to provide visual context before feature list

The screenshot displays the RC110 device connected with dose rate (54.91 nSv/h) and count rate (8.171 cps) monitoring, intelligence analysis, and real-time graphing capabilities.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add this screen shot to the readme</issue_title>
<issue_description>

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add this screen shot to the readme #6

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[darkmatter2222]

@copilot merge on main please

[Copilot]

@copilot merge on main please

I don't have permission to merge to main. You'll need to merge the PR through GitHub's interface - the changes are ready. The screenshot has been added to the README Overview section as requested (commit 6736b8e).