Add sandbox stage builder scripts and functionality

- Introduced StageGizmos for hover highlighting, selection outlines, and rotation handles in the sandbox stage builder.
- Added StageGrid for an optional world-space grid overlay that adjusts with camera panning and zooming.
- Implemented StageSelection for geometric hit-testing and selection management of nodes in the sandbox.
- Created StageSpawner as a registry-driven factory for spawning terrain, props, and stickmen, allowing for dynamic template management.
- Each script includes necessary constants, state management, and public API methods for interaction.

docs/tech_debt_and_optimizations.md

@@ -20,6 +20,8 @@ This document tracks known technical debt, optimization opportunities, and minor
 | 8   | **Rest Timeout UI** — The director can adjust `rest_timeout` via inspector, but there is no in‑world UI in the physics harness yet.                                                                           | Low         | ✅ Resolved | Phase 11: added a Rest `SpinBox` (0.1–10 s, step 0.1) to the harness UI that writes `_rig.rest_timeout` (runtime‑only), plus a "Recover Now" button → `_rig.request_recovery()`. (2026‑08‑27) |
 | 9   | **Animation Generation DRY** — `create_walk.gd` is a standalone script. It should be merged into a unified `create_animations.gd` that also generates `stand_up` and idle animations.                         | Medium      | ✅ Resolved | Phase 11: `create_walk.gd` deleted; new `scripts/create_animations.gd` (`@tool extends EditorScript`) bakes `walk_left`/`walk_right` (same keyframes) and a one‑shot `stand_up` into the scene's `AnimationLibrary` (the baked `stand_up` is an authored reference only — runtime recovery tweens the IK targets directly). (2026‑08‑27) |
 | 10  | **Rig Collision Proxy Re‑addition** — The proxy is re‑added on ragdoll exit, but may cause a brief visual pop if it appears while the kinematic rig is visible.                                               | Low         | Open   | Phase 11 still re‑adds the proxy as soon as `RECOVERING` begins (`state_changed` handler), while `Body/*` is already visible — the static box can pop in around the standing figure before the stand‑up completes. Consider delaying re‑addition until after recovery finishes (`ANIMATED`). (2026‑08‑27) |
+| 11  | **Stage Freeze Abstraction** — Sandbox Stage EDIT‑mode freezing is type‑specific: `RigidBody2D.freeze_mode = FREEZE_MODE_KINEMATIC` for props, `StickmanRig.set_ragdoll(false)` for stickmen, nothing for `StaticBody2D` terrain. There is no unified "freeze" abstraction over the mixed physics population. | Low         | Open   | A future physics type (e.g. `Area2D`‑based sensors) will need another case in `scripts/sandbox_stage.gd` `_enter_edit_mode()` / `_enter_play_mode()`. Consider a duck‑typed `set_simulating(bool)` interface once more physical object kinds appear. (2026‑08‑27) |
+| 12  | **Stage AABB Selection Precision** — `StageSelection.get_world_aabb` uses conservative world‑space AABBs (polygon point union / fixed rig rect), not point‑in‑polygon.                                          | Low         | Open   | Clicks in the bounding‑box corners of large or rotated terrain may select a block even outside its polygon, and overlapping blocks can mis‑select. Refine with `Geometry2D.is_point_in_polygon()` for `TerrainBlock`/`PropBlock` polygons (and circle distance for ball props) once selection precision matters. (2026‑08‑27) |
 
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@@ -50,6 +52,7 @@ This document tracks known technical debt, optimization opportunities, and minor
 | ---------- | -------------------------------------------------------------- |
 | 2026-08-26 | Initial creation — migrated observations from Phase 10 review. |
 | 2026-08-27 | Phase 11 resolved #6 (recovery starting pose), #7 (transition visual pop), #8 (rest timeout UI), #9 (animation generation DRY); #10 (proxy re‑addition) remains open with updated scope. Later revision: stand‑up recovery switched from bridge‑into‑baked‑animation to a direct marker tween (captured pose → `STAND_POSE`), fixing a visible jump; baked `stand_up` kept as authored reference only. Second revision: ragdoll entry builds from the current solved bone positions (IK disabled only after the blend completes) and the recovery snap derives joint ends from capsule half‑heights with Torso `bone_angle` compensation, fixing the entry pose‑pop and the "recovery starts lying" bugs. Third revision: the entire crossfade/blend (`transition_duration`, `BlendDirection`, opacity fade, softness ramp) was **removed on director feedback** — entry is now an instant handoff (build at current pose → hide `Body/*` → disable IK in one call), since the ragdoll spawns at the identical pose and a fade only read as ghosting. |
+| 2026-08-27 | Sandbox Stage Builder (Phase 2) added `scripts/sandbox_stage.gd` + `stage_spawner.gd` / `stage_selection.gd` / `stage_gizmos.gd` + `scenes/sandbox_stage.tscn`. Logged #11 (no unified freeze abstraction over the mixed `StaticBody2D` / `RigidBody2D` / `Node2D` population) and #12 (selection hit‑testing uses world‑space AABBs rather than point‑in‑polygon). |
 
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