ui: move test result and trigger archive to contextual locations

[TerrifiedBug]

Summary

• Show connection test result inline next to the Test Connection button instead of at the bottom next to Save
• Move Trigger Archive button into the top-right of the Last Archive dashboard card

Test plan

• Verify test connection message appears next to the Test Connection button for both NFS and CIFS
• Verify save message still appears next to the Save button
• Verify Trigger Archive button renders in the Last Archive card header

[greptile-apps]

Greptile Summary

This PR improves UI feedback by displaying test connection results inline next to the Test Connection button and relocating the Trigger Archive button to the Last Archive card header for better contextual placement.

• Separated testMessage state from message state in Config.tsx to independently manage test connection feedback
• Both NFS and CIFS test flows now display results inline next to their respective Test Connection buttons
• Trigger Archive button moved from standalone section to Last Archive card header with adjusted sizing (text-xs)
• All functionality preserved - no logic changes, only UI repositioning

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• Clean UI refactoring with no logic changes - only state management separation and element repositioning. All existing functionality preserved, proper React patterns followed, and consistent with codebase styling conventions.
• No files require special attention

Important Files Changed

Filename	Overview
web/src/pages/Config.tsx	Separated test connection feedback into dedicated state and displays it inline next to Test Connection button
web/src/pages/Dashboard.tsx	Moved Trigger Archive button into Last Archive card header for better contextual placement

_{Last reviewed commit: fcc5ff7}