v2.10.4

Changes

• Teacher-coverage mode now samples one course per teacher first, then uses remaining ordinary sample slots for extra courses from teachers on the monthly unreported list.
• If the focus list cannot be read, coverage mode still exports and fills remaining slots in stable order; unreported-priority mode continues to require the list.
• Export reasons and processing notes now show unreported-teacher extra-course counts.

Validation

• TypeScript typecheck and production build passed.
• All 9 inspection sampler checks passed, including coverage followed by focus-teacher frequency allocation.
• git diff --check passed.