refactor: consolidate tests from 15 files to 6 files

Bundle related tests for better organization:
- test_core.py: cache + state + ipc (37 tests)
- test_services.py: weather + location + token_usage + thinking_feed (40 tests)
- test_widget.py: colors + config + pipeline + renderer (49 tests)
- Keep test_daemon.py, test_server.py, test_properties.py as-is

Total: 180 tests across 6 files (down from 15 files)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: shepardxia