chore: remove manager-era NBA test files and one-off debug scripts

The four test_nba_*.py files imported nba_managers, leaderboard_manager
and odds_manager — top-level modules deleted when sports displays became
plugins — inside try/except blocks that swallowed the ImportError, so
they passed while exercising nothing. test_nba_data_structure.py and
debug_nba_api.py (a diagnostic script living in test/) made live ESPN
API calls rather than testing repo code. None were enrolled in CI.

scripts/debug/direct_fix_imports.py and check_imports.py were one-shot
artifacts that edited/inspected a hardcoded ~/LEDMatrix/web_interface/
app.py to fix an import problem solved long ago; nothing references
them.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SXb4mKcAkVaxkeTb3YnAdr

docs/HOW_TO_RUN_TESTS.md

@@ -253,7 +253,6 @@ test/
 ├── test_error_aggregator.py             # Error aggregation tests
 ├── test_schema_manager.py               # Schema manager tests
 ├── test_web_api.py                      # Web API tests
-├── test_nba_*.py                        # NBA-specific test suites
 ├── plugins/                             # Per-plugin test suites
 │   ├── test_clock_simple.py
 │   ├── test_calendar.py