feat: add unit tests for pure logic

Introduces a GLMod.Tests xUnit project covering the parts of the
codebase that don't touch IL2CPP/Among Us types:

- Entities: GLGame, GLPlayer, GLPosition (constructors, mutations,
  turn-aware position routing, GetId error cases)
- Enums: SabotageType / GameMapType extensions
- ServiceManager: enable/disable/exists state transitions
- GameConstants: action-prefix invariants and support-id alphabet

58 tests, all passing. While writing the alphabet test, surfaced a
discrepancy between CLAUDE.md §6 (claimed "no 0, no O") and the actual
SUPPORT_ID_CHARS (only '0' is excluded); fixed the spec to match.

Documents the test scope and CI status in CLAUDE.md §11.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Merge pull request #16 from MatuxGG/claude/add-async-integrity-functi…

…ons-011CUjFNzUMfEev7LcVQEa8b

Add missing async functions to Integrity service

Merge pull request #13 from MatuxGG/claude/fix-http-500-error-011CUhY…

…ChBzEfffqhx2DtbVc

Fix HTTP 500 error in authentication service

8.2.0 - Coroutines version

5.1.7 - getRank small changes

5.1.5 - Ban system

5.1.5 - Sabotages now collected + timestamps as miliseconds

5.1.4 - Colors + positions