## Summary
- derive Go Agent debug input forms from prompt variable references
instead of Agent meta fields
- seed `sys.*` debug params into `CanvasState.Sys` so single-component
debug resolves prompt variables like Python
- restore Agent test-run parity for form rendering and debug execution
## Tests
- `go test ./internal/agent/component -run
'TestAgent_(GetInputForm_UsesPromptReferences|GetInputForm_DeduplicatesPromptReferences|Meta_DefaultsToEmpty|Reset_NoTools)$'`
- `go test ./internal/handler -run
'Test(DebugComponent_SeedsSysInputsIntoCanvasState|DebugComponent_HappyPath_Begin|GetComponentInputForm_HappyPath)$'`
AFTER:
<img width="669" height="456" alt="image"
src="https://github.com/user-attachments/assets/4fd86559-aafc-4027-91ae-6e666137ee1b"
/>
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