Add unit tests for context-detector module

[nikolasdehor]

Description

The context-detector module in .aios-core/core/session/context-detector.js implements hybrid session type detection but has no test coverage.

Proposed Changes

• Add 34 unit tests covering:
  • Hybrid detection (conversation vs file-based)
  • Command extraction from message content
  • Workflow pattern matching (story, epic, backlog)
  • Session state persistence and directory creation
  • Expired session cleanup
  • Session ID generation

Acceptance Criteria

• All 34 tests pass
• No external dependencies required

[nikolasdehor]

Covered by consolidated PR #424