Tailscale Solution: Workbook Preview Images Registered for Standard and Premium Dashboards

What Changed

The WorkbooksMetadata.json registry previously had empty previewImagesFileNames arrays for both Tailscale workbooks. This PR populates those arrays with the correct image filenames and adds the corresponding image assets:

• Tailscale Operations (Standard): tailscalestandardblack.png, tailscalestandardwhite.png
• Tailscale Operations (Premium): tailscalepremiumblack.png, tailscalepremiumwhite.png

The Tailscale SVG logo (Workbooks/Images/Logos/Tailscale.svg) is also added as a new asset. The solution package (3.0.0.zip and mainTemplate.json) is repackaged to include these assets.

This PR carries a P0 label – assess deployment or pipeline breakage risk explicitly. The change itself is cosmetic (preview images for Content Hub display), but P0 labeling may indicate a dependency on these assets for solution gallery rendering or validation pipeline gating.

Affected Files

Workbooks/Images/Logos/Tailscale.svg
Workbooks/Images/Preview/tailscalepremiumblack.png
Workbooks/Images/Preview/tailscalepremiumwhite.png
Workbooks/Images/Preview/tailscalestandardblack.png
Workbooks/Images/Preview/tailscalestandardwhite.png
Workbooks/WorkbooksMetadata.json
(packaging artefacts: 3.0.0.zip, mainTemplate.json)