Fix timezone-aware vs naive datetime comparison in correlate_git_with_sessions

[evansenter]

Problem

The correlate_git_with_sessions() function in queries.py throws a TypeError when comparing timezone-aware and naive datetime objects. This happens when git commits have timezone information but session timestamps don't (or vice versa).

Current Workaround

Tests skip this case with pytest.skip():

try:
    result = correlate_git_with_sessions.fn(days=7)
except TypeError:
    pytest.skip("Timezone comparison issue in correlate_git_with_sessions")

Expected Behavior

The function should handle both timezone-aware and naive datetimes gracefully, either by:

1. Normalizing all datetimes to UTC
2. Stripping timezone info for comparison
3. Making all timestamps timezone-aware

Files Affected

• src/session_analytics/queries.py - correlate_git_with_sessions() function
• tests/test_server.py:225-238 - test with skip workaround
• tests/test_cli.py:626-630 - CLI test with skip workaround

Context

Discovered during test audit in PR #32.