[feature]: Add time estimates to work items (not effort estimates)

Is there an existing issue for this?

• I have searched the existing issues

Summary

Problem

Plane currently has ok time tracking capabilities, but lacks time estimation. While Plane offers "estimate points" for effort/complexity, these are not directly translatable to hours. This makes it difficult to plan sprints, manage client expectations, and track budget burn rates for projects. I'd like to keep time estimates and effort estimates separate.

Current behavior

• Estimate points measure effort/complexity, not time
• No way to set estimated hours on work items
• Cannot compare actual vs estimated time
• Sprint planning for agencies requires manual hour calculations outside Plane

Expected behavior

• Add 'Time Estimate' property to work items (separate from estimate points)
• Display estimate alongside tracked time in all views
• Optionalle show variance/delta between estimated and tracked time (e.g. percentages)
• Enable filtering: time-estimate:>4h, over-estimate, under-estimate
• Sum estimates at parent/work items overview level

Use case

As an agency planning a sprint, I need to:

1. Set both complexity points AND hour estimates (a 1-point bug might take 4h, while a 1-point feature takes 1h)
2. See if we're over/under budget per feature
3. Know if a 40-hour sprint is actually 60 hours of estimated work

Why should this be worked on?

Story points and time estimates serve different purposes. Points help with velocity planning, while hour estimates help with resource allocation and billing. Having both as separate properties would make Plane suitable for both product teams and agencies.