feat: complete Phase 1 infrastructure

- erp-core: error types, shared types, event bus, ErpModule trait
- erp-server: config loading, database/Redis connections, migrations
- erp-server/migration: tenants table with SeaORM
- apps/web: Vite + React 18 + TypeScript + Ant Design 5 + TailwindCSS
- Web frontend: main layout with sidebar, header, routing
- Docker: PostgreSQL 16 + Redis 7 development environment
- All workspace crates compile successfully (cargo check passes)

crates/erp-server/migration/src/lib.rs

@@ -0,0 +1,12 @@
+pub use sea_orm_migration::prelude::*;
+
+mod m20260410_000001_create_tenant;
+
+pub struct Migrator;
+
+#[async_trait::async_trait]
+impl MigratorTrait for Migrator {
+    fn migrations() -> Vec<Box<dyn MigrationTrait>> {
+        vec![Box::new(m20260410_000001_create_tenant::Migration)]
+    }
+}

crates/erp-server/migration/src/m20260410_000001_create_tenant.rs

@@ -0,0 +1,74 @@
+use sea_orm_migration::prelude::*;
+
+#[derive(DeriveMigrationName)]
+pub struct Migration;
+
+#[async_trait::async_trait]
+impl MigrationTrait for Migration {
+    async fn up(&self, manager: &SchemaManager) -> Result<(), DbErr> {
+        manager
+            .create_table(
+                Table::create()
+                    .table(Tenant::Table)
+                    .if_not_exists()
+                    .col(
+                        ColumnDef::new(Tenant::Id)
+                            .uuid()
+                            .not_null()
+                            .primary_key(),
+                    )
+                    .col(ColumnDef::new(Tenant::Name).string().not_null())
+                    .col(
+                        ColumnDef::new(Tenant::Code)
+                            .string()
+                            .not_null()
+                            .unique_key(),
+                    )
+                    .col(
+                        ColumnDef::new(Tenant::Status)
+                            .string()
+                            .not_null()
+                            .default("active"),
+                    )
+                    .col(ColumnDef::new(Tenant::Settings).json().null())
+                    .col(
+                        ColumnDef::new(Tenant::CreatedAt)
+                            .timestamp_with_time_zone()
+                            .not_null()
+                            .default(Expr::current_timestamp()),
+                    )
+                    .col(
+                        ColumnDef::new(Tenant::UpdatedAt)
+                            .timestamp_with_time_zone()
+                            .not_null()
+                            .default(Expr::current_timestamp()),
+                    )
+                    .col(
+                        ColumnDef::new(Tenant::DeletedAt)
+                            .timestamp_with_time_zone()
+                            .null(),
+                    )
+                    .to_owned(),
+            )
+            .await
+    }
+
+    async fn down(&self, manager: &SchemaManager) -> Result<(), DbErr> {
+        manager
+            .drop_table(Table::drop().table(Tenant::Table).to_owned())
+            .await
+    }
+}
+
+#[derive(DeriveIden)]
+enum Tenant {
+    Table,
+    Id,
+    Name,
+    Code,
+    Status,
+    Settings,
+    CreatedAt,
+    UpdatedAt,
+    DeletedAt,
+}