fix: add missing approval workflow columns to ab_directive_log (migration 002)

/approval/pending was returning 500 UndefinedColumnError because the
approval router and MCP get_pending_approvals tool both query columns
(agent_name, action_type, description, context_data, approver_id,
approval_note, updated_at) that were never added in the initial schema
migration 001.

Adds migration 002 to ALTER TABLE ab_directive_log with all seven
missing columns (all nullable so existing rows are unaffected) and an
index on updated_at for efficient polling.

Deploy: after pulling on miaai, run:
  cd /root/odoo/odoo-ai && docker compose exec agent-service \
    alembic -c agent_service/migrations/alembic.ini upgrade head

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

agent_service/migrations/versions/002_approval_columns.py

@@ -0,0 +1,64 @@
+"""Add approval workflow columns to ab_directive_log
+
+The approval router (/approval/pending, /approval/respond) and the MCP
+get_pending_approvals tool both reference columns that were never added
+in the initial schema migration.  This migration adds them so the
+/approval/pending endpoint stops returning 500 UndefinedColumnError.
+
+New columns on ab_directive_log:
+  agent_name    — which specialist agent created the pending-approval entry
+  action_type   — short label for the action type (e.g. 'create_expense')
+  description   — human-readable summary shown in the approval UI
+  context_data  — JSONB bag for any extra context the UI needs to display
+  approver_id   — set when a human approves/rejects (VARCHAR to allow
+                  Odoo user IDs or system strings like '__auto__')
+  approval_note — free-text note from the approver
+  updated_at    — timestamp of last status change; indexed for polling
+
+Revision ID: 002
+Revises: 001
+Create Date: 2026-05-21
+"""
+from alembic import op
+import sqlalchemy as sa
+
+revision = '002'
+down_revision = '001'
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # Add approval-workflow columns to ab_directive_log.
+    # All columns are nullable so existing rows are not affected.
+    op.execute("""
+        ALTER TABLE ab_directive_log
+            ADD COLUMN IF NOT EXISTS agent_name    VARCHAR(64),
+            ADD COLUMN IF NOT EXISTS action_type   VARCHAR(64),
+            ADD COLUMN IF NOT EXISTS description   TEXT,
+            ADD COLUMN IF NOT EXISTS context_data  JSONB,
+            ADD COLUMN IF NOT EXISTS approver_id   VARCHAR(64),
+            ADD COLUMN IF NOT EXISTS approval_note TEXT,
+            ADD COLUMN IF NOT EXISTS updated_at    TIMESTAMP
+    """)
+
+    # Index for quick polling of pending-approval rows by updated_at
+    op.execute("""
+        CREATE INDEX IF NOT EXISTS idx_dir_updated
+        ON ab_directive_log(updated_at DESC)
+        WHERE updated_at IS NOT NULL
+    """)
+
+
+def downgrade() -> None:
+    op.execute("DROP INDEX IF EXISTS idx_dir_updated")
+    op.execute("""
+        ALTER TABLE ab_directive_log
+            DROP COLUMN IF EXISTS updated_at,
+            DROP COLUMN IF EXISTS approval_note,
+            DROP COLUMN IF EXISTS approver_id,
+            DROP COLUMN IF EXISTS context_data,
+            DROP COLUMN IF EXISTS description,
+            DROP COLUMN IF EXISTS action_type,
+            DROP COLUMN IF EXISTS agent_name
+    """)