refactor(migrations): squash 75 migrations into 12 per-module initial migrations

The old migration chain was broken (downgrade path through vendor->merchant
rename made rollbacks impossible). This squashes everything into fresh
per-module migrations with zero schema drift, verified by autogenerate.

Changes:
- Replace 75 accumulated migrations with 12 per-module initial migrations
  (core, billing, catalog, marketplace, cms, customers, orders, inventory,
  cart, messaging, loyalty, dev_tools) in a linear chain
- Fix make db-reset to use SQL DROP SCHEMA instead of alembic downgrade base
- Enable migration autodiscovery for all modules (migrations_path in definitions)
- Rewrite alembic/env.py to import all 75 model tables across 13 modules
- Fix AdminNotification import (was incorrectly from tenancy, now from messaging)
- Update squash_migrations.py to handle all module migration directories

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

app/modules/inventory/definition.py

@@ -145,6 +145,7 @@ inventory_module = ModuleDefinition(
     models_path="app.modules.inventory.models",
     schemas_path="app.modules.inventory.schemas",
     exceptions_path="app.modules.inventory.exceptions",
+    migrations_path="migrations",
     # Metrics provider for dashboard statistics
     metrics_provider=_get_metrics_provider,
     # Feature provider for feature flags

app/modules/inventory/migrations/versions/inventory_001_initial.py

@@ -0,0 +1,69 @@
+"""inventory initial - inventory, inventory transactions
+
+Revision ID: inventory_001
+Revises: orders_001
+Create Date: 2026-02-07
+"""
+from alembic import op
+import sqlalchemy as sa
+
+revision = "inventory_001"
+down_revision = "orders_001"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # --- inventory ---
+    op.create_table(
+        "inventory",
+        sa.Column("id", sa.Integer(), primary_key=True, index=True),
+        sa.Column("product_id", sa.Integer(), sa.ForeignKey("products.id"), nullable=False, index=True),
+        sa.Column("store_id", sa.Integer(), sa.ForeignKey("stores.id"), nullable=False, index=True),
+        sa.Column("warehouse", sa.String(), nullable=False, server_default="strassen", index=True),
+        sa.Column("bin_location", sa.String(), nullable=False, index=True),
+        sa.Column("location", sa.String(), nullable=True, index=True),
+        sa.Column("quantity", sa.Integer(), nullable=False, server_default="0"),
+        sa.Column("reserved_quantity", sa.Integer(), nullable=True, server_default="0"),
+        sa.Column("gtin", sa.String(), nullable=True, index=True),
+        sa.Column("created_at", sa.DateTime(), server_default=sa.func.now(), nullable=False),
+        sa.Column("updated_at", sa.DateTime(), server_default=sa.func.now(), nullable=False),
+        sa.UniqueConstraint("product_id", "warehouse", "bin_location", name="uq_inventory_product_warehouse_bin"),
+    )
+    op.create_index("idx_inventory_store_product", "inventory", ["store_id", "product_id"])
+    op.create_index("idx_inventory_warehouse_bin", "inventory", ["warehouse", "bin_location"])
+
+    # --- inventory_transactions ---
+    # Create the enum type for transaction_type
+    transaction_type_enum = sa.Enum(
+        "reserve", "fulfill", "release", "adjust", "set", "import", "return",
+        name="transactiontype",
+    )
+    op.create_table(
+        "inventory_transactions",
+        sa.Column("id", sa.Integer(), primary_key=True, index=True),
+        sa.Column("store_id", sa.Integer(), sa.ForeignKey("stores.id"), nullable=False, index=True),
+        sa.Column("product_id", sa.Integer(), sa.ForeignKey("products.id"), nullable=False, index=True),
+        sa.Column("inventory_id", sa.Integer(), sa.ForeignKey("inventory.id"), nullable=True, index=True),
+        sa.Column("transaction_type", transaction_type_enum, nullable=False, index=True),
+        sa.Column("quantity_change", sa.Integer(), nullable=False),
+        sa.Column("quantity_after", sa.Integer(), nullable=False),
+        sa.Column("reserved_after", sa.Integer(), nullable=False, server_default="0"),
+        sa.Column("location", sa.String(), nullable=True),
+        sa.Column("warehouse", sa.String(), nullable=True),
+        sa.Column("order_id", sa.Integer(), sa.ForeignKey("orders.id"), nullable=True, index=True),
+        sa.Column("order_number", sa.String(), nullable=True),
+        sa.Column("reason", sa.Text(), nullable=True),
+        sa.Column("created_by", sa.String(), nullable=True),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False, index=True),
+    )
+    op.create_index("idx_inv_tx_store_product", "inventory_transactions", ["store_id", "product_id"])
+    op.create_index("idx_inv_tx_store_created", "inventory_transactions", ["store_id", "created_at"])
+    op.create_index("idx_inv_tx_order", "inventory_transactions", ["order_id"])
+    op.create_index("idx_inv_tx_type_created", "inventory_transactions", ["transaction_type", "created_at"])
+
+
+def downgrade() -> None:
+    op.drop_table("inventory_transactions")
+    op.drop_table("inventory")
+    sa.Enum(name="transactiontype").drop(op.get_bind(), checkfirst=True)