feat(isometric): generic object selection + modal system

[h0lybyte]

Summary

• Add InteractableKind discriminated union (Tree, Crate, Crystal, Pillar, Sphere) as a generic <T> pattern for clickable objects
• Bevy detect_click_selection system writes SelectedObject snapshot on left-click of hovered Interactable entities (take semantics — read clears)
• React useObjectSelection hook polls snapshot every 100ms and opens the existing modal with kind-specific title, description, and action button
• All hoverable entities (trees, crates, crystals, pillars, spheres) now carry Interactable component

Test plan

• Click a highlighted tree — modal opens with "Tree" title and "Chop Tree" button
• Click a highlighted crate — modal opens with "Wooden Crate" and "Open Crate"
• Click crystal/pillar/sphere — corresponding modal content appears
• Close modal, click another object — new modal opens
• Click with nothing hovered — nothing happens
• Action button shows toast confirmation (placeholder)

🤖 Generated with Claude Code

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None