Clean up codebase and fix server host binding for IPv6 support

Cleanup:
- Remove unused aircraft-icon.svg (replaced by type-specific icons)
- Remove test files: beast-dump-with-heli.bin, beast.test, main, old.json, ux.png
- Remove duplicate config.json.example (kept config.example.json)
- Remove empty internal/coverage/ directory
- Move CLAUDE.md to project root
- Update assets.go documentation to reflect current icon structure
- Format all Go code with gofmt

Server Host Binding Fix:
- Fix critical bug where server host configuration was ignored
- Add host parameter to Server struct and NewWebServer constructor
- Rename NewServer to NewWebServer for better clarity
- Fix IPv6 address formatting in server binding (wrap in brackets)
- Update startup message to show correct bind address format
- Support localhost-only, IPv4, IPv6, and interface-specific binding

This resolves the "too many colons in address" error for IPv6 hosts like ::1
and enables proper localhost-only deployment as configured.

Closes #15

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

assets/static/aircraft-icon.svg

@@ -1,5 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="#00a8ff" stroke="#ffffff" stroke-width="1">
-  <path d="M12 2l-2 16 2-2 2 2-2-16z"/>
-  <path d="M4 10l8-2-1 2-7 0z"/>
-  <path d="M20 10l-8-2 1 2 7 0z"/>
-</svg>