Claude/background cot messages (Snapchat#32)

* Fix CoT message handling and add debug logging for teammate display issue

- Add comprehensive debug logging throughout the CoT message pipeline to
  diagnose why teammates may not appear on map
- Fix cotEvents array deduplication by UID to prevent memory growth
- Add stale event cleanup (removes events older than 1 hour every 5 min)
- Improve CoT point parsing to handle different XML formats
- Add detailed logging at network receive, parsing, and event handling stages
- Log warnings when takService reference is nil (would prevent map updates)

This helps diagnose issues where users connect to TAK servers but don't
see their teammates on the map.

* Fix unit filtering to show all affiliations by default

- Changed showUnknown default from false to true (show unknown units)
- Added showNeutral toggle for neutral units (a-n-*)
- Updated filter logic to handle ALL MIL-STD-2525 affiliations:
  - Friendly group: a-f (friendly), a-k (faker), a-a (assumed friendly)
  - Hostile group: a-h (hostile), a-j (joker), a-s (suspect)
  - Neutral: a-n
  - Unknown: a-u and any other unrecognized 'a-' types
- Non-affiliation CoT types (waypoints, markers) are ALWAYS shown
- Added Neutral toggle button to Layers panel
- Philosophy: Default to showing MORE rather than potentially missing units

This ensures teammates from OpenTAKServer are displayed regardless of
what affiliation their CoT messages report.

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Co-authored-by: Claude <noreply@anthropic.com>

Author: jfuginay