feat(broadcast): add getSelection/setSelection and selectionUpdate

[jtj70]

This adds the two remaining broadcast methods listed in the TODO checklist in packages/broadcast/src/types.ts: getSelection / setSelection, plus a selectionUpdate event so external callers can react to selection changes made inside the app (clicks, marquee, etc.), not just ones they initiated themselves.

What's included

• New SerializedSelectionState { nodeIds: string[]; edgeIds: string[] } wire type, independent of the internal SelectionState (which can only be nodes or edges at a time). deserializeSelection documents the precedence rule for the case where both arrays are non-empty: nodeIds wins, since Gephi Lite cannot represent a simultaneous nodes+edges selection today.
• BroadcastClient binds to the existing selectionAtom and only emits selectionUpdate when the effective selection actually changes. Atoms compare by reference, so a content-level check (selectionStatesAreEqual) was needed to avoid firing on every no-op select()/setSelection() call, and to avoid echo-loops when a caller sets back a selection it just received.
• setGraphDataset now prunes the current selection against the new dataset (pruneSelectionToGraph), keeping ids that still exist and clearing the rest. Previously a dataset swap over broadcast could leave a stale selection referencing nodes/edges that no longer exist.
• setSelection prunes unknown ids the same way, so a caller can't pollute the internal state with ids that don't exist in the current graph.
• Small, necessary side fix: ITypedEventEmitter's listener typing assumed every event was argument-less (true for the only existing event, newInstance). Generalized it via a new EventListener<F> helper so a listener can correctly receive an event's data, typed from its declared return type — needed because selectionUpdate is the first event to actually carry a payload.

Tests

packages/gephi-lite/src/core/broadcast/client.spec.ts, 4 cases:

• getSelection returns the current selection
• setSelection changes the selection and emits selectionUpdate
• setGraphDataset keeps still-valid selected ids and drops stale ones
• no selectionUpdate when the effective selection doesn't change

Separately noticed, not part of this PR

While testing setGraphDataset, I found a pre-existing, unrelated bug: filteredGraphAtom (core/graph/index.ts) is a derivedAtom without checkOutput: false, and lodash.isEqual treats any two different graphology Graph instances of equal node/edge count as equal — so a same-size dataset swap can leave it silently stale, which can later make resetCamera() throw. Reproduces without any of this PR's changes. Not fixing it here to keep this PR focused; happy to open a separate issue/PR if useful.

Open questions for maintainers

Very open to a different wire shape for SerializedSelectionState or different dataset-replacement semantics if you'd prefer something else here — this is meant as a starting point matching the existing getFilters/setFilters pattern, not a fixed proposal.