Sd/fix invalid date issue

[shatd]

Hi Ramin,

Fix: Prevent crashes when selecting extremely long date ranges

Problem

When users attempt to select extremely long date ranges (e.g., moving the calendar too far), the app crashes with invalid date objects ({from: Invalid Date, to: Invalid Date}), resulting in NaN values in labels and broken UI state.

Root Cause

• Date calculations in slider utilities didn't validate input dates before diffing
• Missing guards in calendar popover range extension logic
• No fallback handling for invalid date propagation in UI rendering

Solution

• Created normalizeDateRange() shared helper to safely normalize and validate date ranges
• Applied defensive guards in createSliderValues and deriveSelectionFromLayout to clamp invalid dates
• Updated date label rendering and selection display to handle invalid dates gracefully
• Fixed numeric safeguards to prevent NaN propagation (e.g., count - 1 division, Number.isFinite() checks)

Changes

• ✅ Added normalize-date-range.ts utility
• ✅ Updated slider value calculations with date validation
• ✅ Added safe fallbacks in label rendering
• ✅ Guards against invalid date operations in calendar popover

Testing

Build passes without errors. Date range selection now remains stable even with extreme calendar movements.

[raminious]

Hi @shatd
I appreciate the PR. Before proceeding with the merge, could you please provide the steps to reproduce the bug so that I can understand the issue?

[shatd]

Hi @raminious ,