Add Progress Indicators (Spinner + Upload Progress Bar)

# User story
As a user, I want visible progress indicators (progress bar + spinner) so I know when the app is validating or uploading.

# Acceptance criteria
- [ ] Add a non-blocking spinner or status indicator for “thinking” states (validation, job start, refreshing).
- [ ] Add a progress bar that updates during an active upload based on job callbacks, console parsing, or inferred internal states.
- [ ] Progress bar clearly displays transitions: starting → uploading → finishing → completed/error.
- [ ] Indicators freeze the UI during job upload process.

Definition of Done:
The UI progress indicators reliably reflect upload states during tests with varying data sizes.

# Sprint Ready Checklist
- [ ] 1. Acceptance criteria defined
- [ ] 2. Team understands acceptance criteria
- [ ] 3. Team has defined solution / steps to satisfy acceptance criteria
- [ ] 4. Acceptance criteria is verifiable / testable
- [ ] 5. External / 3rd Party dependencies identified
- [ ] 6. Ticket is prioritized and sized

# Notes
*Add any helpful notes here.*