refactor: реструктуризация — core/, db/, routes/, web/

guarddog_nexus/
├── core/          scanner, harvester, nexus, llm
├── db/            engine, models, queries
├── routes/        webhooks, api_*, web
└── web/           templates + static

- 11 файлов перемещено (git mv — сохранена история)
- Все импорты обновлены (~15 файлов)
- main.py, tests — исправлены пути
- 50/50 тестов, ruff clean

guarddog_nexus/db/models.py

@@ -0,0 +1,56 @@
+"""SQLAlchemy ORM models."""
+
+import datetime
+from enum import Enum
+
+from sqlalchemy import JSON, Boolean, DateTime, ForeignKey, Integer, String, Text, func
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from guarddog_nexus.db.engine import Base
+
+
+class ScanStatus(str, Enum):
+    PENDING = "pending"
+    SCANNING = "scanning"
+    COMPLETED = "completed"
+    FAILED = "failed"
+
+
+class Scan(Base):
+    __tablename__ = "scans"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    package_name: Mapped[str] = mapped_column(String(255), nullable=False)
+    package_version: Mapped[str] = mapped_column(String(255), nullable=False)
+    ecosystem: Mapped[str] = mapped_column(String(50), nullable=False, default="pypi")
+    repository: Mapped[str] = mapped_column(String(255), nullable=False)
+    nexus_asset_url: Mapped[str] = mapped_column(Text, nullable=False)
+    sha256: Mapped[str | None] = mapped_column(String(64), nullable=True)
+    status: Mapped[str] = mapped_column(
+        String(20), nullable=False, default=ScanStatus.PENDING.value
+    )
+    total_findings: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
+    flagged: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+    started_at: Mapped[datetime.datetime] = mapped_column(
+        DateTime, nullable=False, default=func.now()
+    )
+    finished_at: Mapped[datetime.datetime | None] = mapped_column(DateTime, nullable=True)
+    error_message: Mapped[str | None] = mapped_column(Text, nullable=True)
+
+    findings: Mapped[list["Finding"]] = relationship(
+        "Finding", back_populates="scan", cascade="all, delete-orphan"
+    )
+
+
+class Finding(Base):
+    __tablename__ = "findings"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    scan_id: Mapped[int] = mapped_column(Integer, ForeignKey("scans.id"), nullable=False)
+    data: Mapped[dict] = mapped_column(JSON, nullable=False)
+    report: Mapped[dict | None] = mapped_column(JSON, nullable=True)
+    created_at: Mapped[datetime.datetime] = mapped_column(
+        DateTime, nullable=False, default=func.now()
+    )
+
+    scan: Mapped["Scan"] = relationship("Scan", back_populates="findings")