refactor(core)!: remove interactiveNodes & the built-in pointer hit-test

[chiefcll]

Why

Stage.interactiveNodes is a Set<CoreNode> that nodes add themselves to via the interactive setter — but nothing ever removes them (no delete exists anywhere, and CoreNode.destroy() doesn't touch it). Since the Set holds a strong reference, every destroyed interactive node — and its whole subtree of props/transforms/texture refs — is pinned for the life of the session. On a long-lived embedded session this leaks one node per destroyed interactive node, and also slows every hit-test as the Set grows.

This was flagged as a HIGH-severity leak in the audit behind #56. Per direction, rather than patch the accounting we're removing the whole feature, which existed only to back a rarely-used built-in pointer hit-test.

What's removed

• Stage.interactiveNodes, Stage.findNodesAtPoint(), Stage.getNodeFromPosition()
• the exported Point type (only used by those hit-test signatures)
• CoreNode interactive getter/setter, the interactive prop on CoreNodeProps (and therefore the public INodeProps), its constructor handling, and its default in Stage.resolveNodeDefaults
• pointInBound() in core/lib/utils — dead once the hit-test was gone (not part of the public exports/)
• examples/tests/detect-touch.ts — a demo of this exact feature (examples auto-discover via glob, so no registry edit needed; it had no visual-regression snapshot)

⚠️ Breaking changes

• node.interactive / interactive: true in props no longer exists.
• renderer.stage.getNodeFromPosition() and findNodesAtPoint() are gone.
• The Point type is no longer exported.

Apps that relied on the built-in hit-test should do point-in-bounds testing against their own node references in application code (the engine no longer maintains a global interactive registry).

Testing

• pnpm build clean; full unit suite green (266 tests); lint clean (lint-staged on commit).
• No new tests — this is a pure removal; existing suites still pass and no test referenced the feature.
• No visual-regression impact (no snapshot existed for the removed example).

Note: I hit stale incremental dist-vitest/ artifacts locally (compiled test files lingering from another branch's build) producing phantom failures — purged with a clean rebuild. CI builds fresh, so it's unaffected.

🤖 Generated with Claude Code

[chiefcll]

SolidTV has it's own useMouse and touch detection.