fix: hour level granularity in hour mode

[Waishnav]

Fixes #534

Problem

Tasks with hour-level precision (e.g., 9:00 AM - 3:00 PM) were being extended to full days, making the Hour view unusable for tasks shorter than 24 hours.

Solution

• Task Processing: Preserve exact hour timing for Hour/Quarter Day/Half Day views instead of auto-extending to full days
• Duration Calculation: Use precise hour-based calculations for sub-day view modes
• Grid Setup: Maintain exact start times without resetting hours to 00:00:00
• Popup Display: Show hour/minute information and duration in hours for relevant views

Screenshot