build: 打通 FastAPI 与 Vue 最小工程、依赖与数据库连接

后端入口、配置、Redis 与 Alembic 迁移就位；前端 Vite 工程可安装可构建。

backend/alembic/versions/idx_kq_org_status_001.py

@@ -0,0 +1,35 @@
+"""Index knowledge_queue by organization and status
+
+The plan's source limit now counts the crawls still queued or running, so
+every file upload and URL add reads this table. It had no index beyond the
+primary key and priority, and nothing purges completed rows, so that read
+was a sequential scan of every tenant's history.
+
+Revision ID: idx_kq_org_status_001
+Revises: add_mcp_usage_guidance_001
+Create Date: 2026-09-18
+"""
+from typing import Sequence, Union
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+# Keep revision ids under 32 characters: alembic_version.version_num is
+# varchar(32), and a longer id upgrades the schema then fails to record
+# itself, so every later start retries and crashes.
+revision: str = 'idx_kq_org_status_001'
+down_revision: Union[str, None] = 'add_mcp_usage_guidance_001'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+INDEX_NAME = 'ix_knowledge_queue_org_status'
+
+
+def upgrade() -> None:
+    op.create_index(
+        INDEX_NAME, 'knowledge_queue', ['organization_id', 'status'], unique=False
+    )
+
+
+def downgrade() -> None:
+    op.drop_index(INDEX_NAME, table_name='knowledge_queue')