fix(cleanup): resolve 9 low-priority issues (P34-P42)

P34: Remove test_sample plugin from production code
P35: Remove CompanyContact=None dead code from contact.py
P36: Change Plugin.config from Text to JSONB (model + migration 0117 + service)
P37: Add AI comment about workspace overengineering in workspace.py
P38: Add container resource limits to docker-compose.yaml
P39: Guest TTL 1800 not found — already migrated to regular users
P40: Add AI comment about missing IP/Device binding in session.py
P41: Fix Redis healthcheck to use auth password
P42: RLS migration history comment already present in alembic/env.py

alembic/versions/0117_plugin_config_text_to_jsonb.py

@@ -0,0 +1,39 @@
+"""Change plugins.config column from Text to JSONB.
+
+The config column was stored as a JSON string in a Text column.
+This migration converts it to native JSONB for proper querying and validation.
+
+Revision ID: 0117
+Revises: 0116
+"""
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects.postgresql import JSONB
+
+revision = "0117"
+down_revision = "0116"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # Convert Text column to JSONB, casting existing JSON strings
+    op.alter_column(
+        "plugins",
+        "config",
+        existing_type=sa.Text(),
+        type_=JSONB,
+        postgresql_using="config::jsonb",
+    )
+
+
+def downgrade() -> None:
+    # Convert back to Text, casting JSONB to text
+    op.alter_column(
+        "plugins",
+        "config",
+        existing_type=JSONB,
+        type_=sa.Text(),
+        postgresql_using="config::text",
+    )