Support route modification during active navigation

[LourenzBani]

Problem

Users cannot change route preferences or destinations once navigation has started.

Current Behavior

• Navigation session becomes fixed after initialization.
• Mid-trip route modifications are not supported.

Expected Behavior

• Users should be able to update route requests while navigating.
• System should recalculate routes without restarting the trip.

Examples

• "Avoid toll roads"
• "Find a faster route"
• "Change destination"

Priority

Medium