v0.2.0: CRM/ERP 系统升级 - 清理 .gitignore 并移除误提交的 venv/env/db 文件

- 更新 .gitignore：全面覆盖环境变量、数据库、日志、缓存、上传文件
- 移除误跟踪的 server/venv/、crm_data.db、.env 文件
- 新增 server/.env.example 模板
- 新增合同管理、利润核算、AI教练等功能模块
- 新增 Playwright e2e 测试套件
- 前后端多项功能升级和 bug 修复

server/alembic/versions/20260327_phase_c_mwa_profit.py

@@ -0,0 +1,57 @@
+"""Phase C: MWA inventory + profit accounting
+
+Revision ID: f6a7b8c9d0e1
+Revises: e5f6a7b8c9d0
+Create Date: 2026-03-27
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects.postgresql import UUID
+
+revision = "f6a7b8c9d0e1"
+down_revision = "e5f6a7b8c9d0"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # ── 1. erp_sku_inventory 新增 mwa_unit_cost ──
+    op.add_column(
+        "erp_sku_inventory",
+        sa.Column("mwa_unit_cost", sa.Numeric(12, 4), server_default="0",
+                  comment="移动加权均价 (Moving Weighted Average)"),
+    )
+
+    # ── 2. erp_inventory_flows 新增 purchase_unit_price + is_special_zero_cost ──
+    op.add_column(
+        "erp_inventory_flows",
+        sa.Column("purchase_unit_price", sa.Numeric(12, 2), server_default="0",
+                  comment="入库采购单价"),
+    )
+    op.add_column(
+        "erp_inventory_flows",
+        sa.Column("is_special_zero_cost", sa.Boolean, server_default="false",
+                  comment="特殊零元入库标识，不参与 MWA 计算"),
+    )
+
+    # ── 3. erp_order_item_costs 新表 ──
+    op.create_table(
+        "erp_order_item_costs",
+        sa.Column("id", UUID(as_uuid=True), primary_key=True),
+        sa.Column("order_item_id", UUID(as_uuid=True),
+                  sa.ForeignKey("erp_order_items.id"), nullable=False, unique=True),
+        sa.Column("purchase_unit_price", sa.Numeric(12, 4), nullable=False,
+                  comment="MWA 成本快照"),
+        sa.Column("profit_amount", sa.Numeric(14, 2), server_default="0",
+                  comment="利润额 = (售价-成本)*数量"),
+        sa.Column("profit_rate", sa.Numeric(5, 4), server_default="0",
+                  comment="利润率"),
+        sa.Column("created_at", sa.DateTime, server_default=sa.func.now()),
+    )
+
+
+def downgrade() -> None:
+    op.drop_table("erp_order_item_costs")
+    op.drop_column("erp_inventory_flows", "is_special_zero_cost")
+    op.drop_column("erp_inventory_flows", "purchase_unit_price")
+    op.drop_column("erp_sku_inventory", "mwa_unit_cost")