Phase 4: student views, opt-outs, and class schedule

Student page with a standing summary, a class-comparison histogram
(zero-dependency HTML/CSS) with a plain-language fewer/same/more
sentence, opt-out management with withdrawal of future dates, and a
call history that respects the per-course assessment-visibility
setting and never shows pending or skipped calls. Opt-outs validate
against a new per-course class-day schedule (range generator plus
individual add/remove for holidays), since Canvas has no structured
meeting-day data; courses without a schedule fall back to a free date
picker. Dev mode seeds a Tue/Thu pattern.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

migrations/versions/37acdb847a25_class_days.py

@@ -0,0 +1,37 @@
+"""class days
+
+Revision ID: 37acdb847a25
+Revises: ad7e3f5ea2f3
+Create Date: 2026-07-31 16:40:25.479997
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = '37acdb847a25'
+down_revision: Union[str, None] = 'ad7e3f5ea2f3'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table('class_days',
+    sa.Column('id', sa.Integer(), nullable=False),
+    sa.Column('course_id', sa.Integer(), nullable=False),
+    sa.Column('date', sa.Date(), nullable=False),
+    sa.ForeignKeyConstraint(['course_id'], ['courses.id'], ),
+    sa.PrimaryKeyConstraint('id'),
+    sa.UniqueConstraint('course_id', 'date')
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_table('class_days')
+    # ### end Alembic commands ###