feat: improve data import and handling in ode desktop

[najuna-brian]

Description

Improves ODE Desktop import/sync handling by building on the original migration work

• Adds stronger staged import flow for JSON + attachments
• Adds schema-aware validation (AJV + formplayer formats) and attachment reference checks
• Adds recursive folder drag-and-drop collection for import staging
• Improves sync/import UX with clear in-progress states and cross-screen status messaging
• Adds timeout guards to prevent long-running sync operations from appearing stuck

[r0ssing]

Thanks @najuna-brian ! This will really improve the desktop experience