fix(ui): hold scan feedback for one second

[terrytan95]

Keeps the manual scan processing state visible long enough for users to perceive that the action was accepted. The shared refresh flow measures elapsed scan time and delays only the terminal success or error state when manual status feedback is requested.

Key Changes

• Enforce a one-second minimum processing state for manual scans
• Preserve immediate completion when the actual scan already exceeds one second
• Apply the same timing to success and failure without delaying startup scans

Verification & Testing

• yarn typecheck
• yarn test src/InventoryWorkspace.test.tsx --run

Impact & Risk

None.