0.2.33: exited positions (secondary-sale edge case)

A member who sold/transferred their stake showed a phantom -100% loss
($0 ending balance, no distribution through the fund). Now:
- entity_access.exited_on (migration e1f2a3b4c5d6), set/cleared from the
  Partners tab (writer-only, inline date picker, audited)
- LP portal card shows a quiet "Exited <date>" badge, keeps documents,
  hides balance/gain
- portfolio summary excludes exited positions ("Excludes N exited")
- fund committed totals (rollup + Partners tab) skip exited members so
  seller + buyer are not double-counted

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/alembic/versions/e1f2a3b4c5d6_access_exited_on.py

@@ -0,0 +1,27 @@
+"""add entity_access.exited_on (member sold/transferred their stake)
+
+Revision ID: e1f2a3b4c5d6
+Revises: d0e1f2a3b4c5
+Create Date: 2026-07-03 10:30:00.000000
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision: str = 'e1f2a3b4c5d6'
+down_revision: Union[str, None] = 'd0e1f2a3b4c5'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    with op.batch_alter_table('entity_access', schema=None) as batch_op:
+        batch_op.add_column(sa.Column('exited_on', sa.Date(), nullable=True))
+
+
+def downgrade() -> None:
+    with op.batch_alter_table('entity_access', schema=None) as batch_op:
+        batch_op.drop_column('exited_on')