feat: edge edit mode + proxmox container mode toggle

- Double-click any link to open Edit Link modal (type, label, VLAN ID, delete)
- Add updateEdge / deleteEdge actions to canvasStore
- Add container_mode field to proxmox nodes (backend model, schemas, migration)
- NodeModal shows container toggle for proxmox type (defaults ON)
- ProxmoxGroupNode renders as regular BaseNode when container_mode is OFF
- setProxmoxContainerMode store action handles structural changes atomically
  (children parentId/extent, node dimensions)
- CanvasContainer filters edges between container proxmox and its children
- Canvas load respects container_mode when assigning parentId/extent

backend/app/db/database.py

@@ -1,3 +1,5 @@
+from contextlib import suppress
+
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
 from sqlalchemy.orm import DeclarativeBase
 
@@ -18,6 +20,9 @@ class Base(DeclarativeBase):
 async def init_db() -> None:
     async with engine.begin() as conn:
         await conn.run_sync(Base.metadata.create_all)
+        # Add container_mode column if not present (existing databases)
+        with suppress(Exception):
+            await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN container_mode BOOLEAN NOT NULL DEFAULT 0")
 
 
 async def get_db():

backend/app/db/models.py

@@ -1,7 +1,7 @@
 import uuid
 from datetime import UTC, datetime
 
-from sqlalchemy import JSON, DateTime, Float, ForeignKey, Integer, String, Text
+from sqlalchemy import JSON, Boolean, DateTime, Float, ForeignKey, Integer, String, Text
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
 from app.db.database import Base
@@ -33,6 +33,7 @@ class Node(Base):
     pos_x: Mapped[float] = mapped_column(Float, default=0)
     pos_y: Mapped[float] = mapped_column(Float, default=0)
     parent_id: Mapped[str | None] = mapped_column(String, ForeignKey("nodes.id"))
+    container_mode: Mapped[bool] = mapped_column(Boolean, default=False)
     last_seen: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
     response_time_ms: Mapped[int | None] = mapped_column(Integer)
     created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=_now)