Group captured/destroyed structures and inbound nuke notifications to reduce clutter

**Is your feature request related to a problem? Please describe.**
When a player gets invaded or bombed in high volume, the event log gets flooded with a ton of individual "Your City was destroyed", "Your City was captured", or "atom bomb inbound" messages. Having to manually count all these messages to figure out how many nukes are currently in coming is frustrating.

**Describe the solution you'd like**
Group identical or related event notifications that occur in quick succession (within a 30-tick / 3 second window) into a single aggregated message:
- E.g., instead of 4 separate "Your City was destroyed" lines, display: `"Your 4 Cities were destroyed"`.
- Instead of multiple separate capture/loss lines, display: `"Captured 4 Cities from [Player]"` or `"Your 4 Cities were captured by [Player]"`.
- Group incoming nukes, showing: `"[Player] - 3 atom bombs inbound"` instead of spamming separate inbound alerts.

**Describe alternatives you've considered**
Disabling notifications for structure losses entirely. However, this hides a feature I previously found useful.
**Additional context**
I have implemented these changes on a local branch (`feature/group-event-messages`) and will submit a Pull Request linking to this issue!
**Assignment**

- [x] I'd like to be assigned to this issue and work on it myself