refactor: 仓库结构扁平化 + PHP前端合并到Nexus仓库

- 将 Nexus/Nexus/* 移到仓库根目录（消除双层嵌套）
- 删除旧的多层空壳目录 (server/, web/, agent/, deploy/, docs/)
- 将PHP前端 (web/) 合并进Nexus仓库 — 统一管理
- 部署时 git clone Nexus 仓库即可，不再需要两个仓库

目录结构：
  server/     ← Python FastAPI后端
  web/        ← PHP前端 (install.php, config.php, etc)
  deploy/     ← Supervisor + Shell健康检查
  docs/       ← 部署文档
  tests/      ← 测试
  .env        ← 不在git中 (install.php生成)
  .gitignore  ← 排除 .env, SECRETS.md

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

server/infrastructure/database/script_repo.py

@@ -0,0 +1,71 @@
+"""Nexus — Script & ScriptExecution Repository (Async SQLAlchemy)"""
+
+from typing import Optional, List
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from server.domain.models import Script, ScriptExecution
+
+
+class ScriptRepositoryImpl:
+    def __init__(self, session: AsyncSession):
+        self.session = session
+
+    async def get_by_id(self, id: int) -> Optional[Script]:
+        result = await self.session.execute(select(Script).where(Script.id == id))
+        return result.scalar_one_or_none()
+
+    async def get_all(self) -> List[Script]:
+        result = await self.session.execute(select(Script).order_by(Script.id))
+        return list(result.scalars().all())
+
+    async def get_by_category(self, category: str) -> List[Script]:
+        result = await self.session.execute(
+            select(Script).where(Script.category == category).order_by(Script.id)
+        )
+        return list(result.scalars().all())
+
+    async def create(self, script: Script) -> Script:
+        self.session.add(script)
+        await self.session.commit()
+        await self.session.refresh(script)
+        return script
+
+    async def update(self, script: Script) -> Script:
+        await self.session.commit()
+        await self.session.refresh(script)
+        return script
+
+    async def delete(self, id: int) -> bool:
+        script = await self.get_by_id(id)
+        if script:
+            await self.session.delete(script)
+            await self.session.commit()
+            return True
+        return False
+
+
+class ScriptExecutionRepositoryImpl:
+    def __init__(self, session: AsyncSession):
+        self.session = session
+
+    async def get_by_id(self, id: int) -> Optional[ScriptExecution]:
+        result = await self.session.execute(
+            select(ScriptExecution).where(ScriptExecution.id == id)
+        )
+        return result.scalar_one_or_none()
+
+    async def create(self, execution: ScriptExecution) -> ScriptExecution:
+        self.session.add(execution)
+        await self.session.commit()
+        await self.session.refresh(execution)
+        return execution
+
+    async def update_status(self, id: int, status: str, results: str) -> ScriptExecution:
+        execution = await self.session.get(ScriptExecution, id)
+        if execution:
+            execution.status = status
+            execution.results = results
+            await self.session.commit()
+            await self.session.refresh(execution)
+        return execution