[UI-12] Add autocomplete placeholder to Tools

[olaservo]

Labels: v2, enhancement
Files: client/src/pages/Tools.tsx

Add UI for autocomplete suggestions in tool argument inputs.

Tasks

• Add autocomplete UI for tool arguments
• Show "Suggestions: ..." below input fields
• Placeholder for completion/complete integration
• Support dropdown selection of suggestions

[olaservo]

Completed in both prototypes. Closing as part of cleanup before tech stack finalization.