Security fixes: P0-P2 complete (22 fixes)

P0 (7): Auth-bypass removed, migrations fixed, plugin-upload disabled, RLS FORCE+WITH CHECK, plugin double-registration fixed, persistent volume, domain removed
P1 (11): User/tenant model, Redis centralized, worker separated, transactional outbox, XSS fixed, DMS chunked streaming, permissions unified, password reset, metrics secured, config/docs fixed, cross-tenant FK
P2 (4): Contact model normalized, cross-imports reduced 94%, commands+state machines for contacts/dms/mail/calendar, SPA path-traversal

8 new migrations, 99 unit tests, 13 commands, 8 contracts, 72 files changed

alembic/versions/0038_dms_content_hash.py

@@ -0,0 +1,44 @@
+"""Add content_hash column to files table for SHA-256 dedup and integrity.
+
+Revision ID: 0038_dms_content_hash
+Revises: 0037_user_tenant_model
+Create Date: 2026-07-25
+
+Changes:
+1. Add content_hash (String(64), nullable) column to files table.
+"""
+
+from __future__ import annotations
+
+from typing import Union
+
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers
+revision: str = "0038_dms_content_hash"
+down_revision: Union[str, None] = "0037_user_tenant_model"
+branch_labels: Union[str, None] = None
+depends_on: Union[str, None] = None
+
+
+def _column_exists(table: str, column: str) -> str:
+    """Return SQL that checks if a column exists on a table."""
+    return (
+        f"SELECT 1 FROM information_schema.columns "
+        f"WHERE table_name = '{table}' AND column_name = '{column}'"
+    )
+
+
+def upgrade() -> None:
+    conn = op.get_bind()
+    result = conn.execute(sa.text(_column_exists("files", "content_hash"))).fetchone()
+    if result is None:
+        op.add_column("files", sa.Column("content_hash", sa.String(64), nullable=True))
+
+
+def downgrade() -> None:
+    conn = op.get_bind()
+    result = conn.execute(sa.text(_column_exists("files", "content_hash"))).fetchone()
+    if result is not None:
+        op.drop_column("files", "content_hash")