Implement interactive prop handling for StickmanRig

- Added PropTrajectory class for deterministic ballistic calculations.
- Introduced StickmanPropInteraction component to manage prop interactions (pickup, drop, throw).
- Implemented grip resolution and attachment logic for props.
- Added signals for interaction events (prop_picked_up, prop_dropped, prop_thrown).
- Defined specifications for prop interaction lifecycle and event rules.
- Ensured compatibility with existing prop systems and added new capabilities for prop pickup.

docs/tech_debt_and_optimizations.md

@@ -107,6 +107,7 @@ This document tracks known technical debt, optimization opportunities, and minor
 | 2026-09-22 | Phase 10a whole-prop transform extension approved and implemented (`specs/phase_10a_prop_scaling.md` §3.4). The prior Resize Whole Prop toggle becomes one **Transform Whole Prop** tool that mirrors Arrange: drag visible geometry to move the whole document, drag the union rotation dot to rotate it about canonical `(0,0)`, and drag a corner for the existing uniform origin-based resize. Move translates every point and non-origin anchor (snapping the baseline delta when Snap is ON); rotate transforms every point/anchor position and adds the angle to editable anchor orientations; circle radius changes only on resize. All gestures preview from snapshots outside authoritative save state and commit once on release; Esc cancellation, selection restoration, mode lifecycle, `.prop` v1.0, and deferred document undo remain unchanged. |
 | 2026-09-22 | Phase 10a implementation and final UI were user verified. The Arrange top bar is ordered **Transform Whole Prop**, **Normalize Size**, **Center Prop**, **Show Stickman Guide**; the numeric scale textbox and Apply Scale button are removed. Transform Whole Prop and Normalize Size are hidden in Reshape and Attach, while Center Prop and Show Stickman Guide remain available. Whole-prop move, 15-degree Ctrl rotation, uniform resize, anchor following, Snap movement, and Esc cancellation are documented in `docs/prop_editor_user_guide.md`; focused tests and the Prop Editor startup smoke test passed. |
 
+| 2026-09-23 | Phase 11 interactive-prop specification written (specs/phase_11_prop_interaction.md), awaiting user sign-off. Approved direction: gated 11A pickup/drop plus triggers, 11B deterministic exact-target throws, and 11C ragdoll disarm; add a backward-compatible pickup capability defaulting true so authored props such as trees can opt out; preserve grip anchors into PropBlock and reuse PropAnchorData; serialize queue prop targets by scene object ID; keep held props under World; dispatch prop events through SandboxStage; cap throws by a tunable 900 px/s launch speed and 0.35–1.5 s flight time. No implementation or debt-status changes are recorded in this entry. |
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 _End of Log_