[TS] Force explicit override & property access (#1006)

Enables TypeScript rules that improve code legibility.

- Requires `override` keyword
- Prevent indexed properties from being accessed with dot notation

```ts
const obj: Record<string, unknown> = {}

// Prefer
obj["property"]

// Over
obj.property
```

src/subgraph/SubgraphSlotBase.ts

@@ -21,7 +21,7 @@ export abstract class SubgraphSlot extends SlotBase implements SubgraphIO, Seria
 
   readonly linkIds: LinkId[] = []
 
-  readonly boundingRect: Rect = [0, 0, 0, SubgraphSlot.defaultHeight]
+  override readonly boundingRect: Rect = [0, 0, 0, SubgraphSlot.defaultHeight]
 
   override get pos() {
     return this.#pos