Implement Phase 17a Prop Roles UI/UX Specification and associated functionality

- Added UI/UX specification for prop roles and set down mechanics in phase 17a.
- Created `PropStageRoles` script to manage normalized behavior for props, including depth, motion, and collision settings.
- Introduced `StagePhysicsPolicy` for shared physics configurations related to props and actors.
- Developed comprehensive tests for prop roles, including default settings, legacy migration, serialization, and runtime behavior.
- Ensured proper handling of set down actions, including clearance and orientation preservation.

.codex/agents/architect.toml

@@ -13,6 +13,15 @@ You are the Lead Systems Architect specializing in Godot 4 and idiomatic GDScrip
 3. **Design:** Define API payload shapes, static GDScript type hints, node hierarchies, and signal flows.
 4. **Log:** Append trade-offs to `docs/architecture/tech_debt_and_optimizations.md`.
 
+### Shared Stage inspector UI
+For an in-stage selected-object inspector, first read `docs/specs/stage_panel_ui_system.md`
+and inspect `scripts/shared/stage_ui/` plus the `stage_panels` theme tokens. Use the existing
+`StageInspectorPanel`, `StagePanelChoiceGroup`, and `StagePanelToggleRow` contracts as the
+starting point; propose extending them before adding duplicate panel controls or styling.
+State explicitly in the spec which shared pieces the feature adopts or extends. The kit is
+currently scoped to in-stage inspector cards, so evaluate dialogs and other editor workflows
+on their own interaction needs instead of forcing this component hierarchy onto them.
+
 ---
 
 ## TWO-PHASE WORKFLOW

.codex/agents/uiux.toml

@@ -7,6 +7,14 @@ sandbox_mode = "read-only"
 developer_instructions = """
 ## 1. Kid-Friendly UI Guardrails (10-Year-Old Persona)
 
+* **Shared Stage Inspector UI:** Before proposing an in-stage selected-object inspector, read
+  `docs/specs/stage_panel_ui_system.md` and inspect the existing controls in
+  `scripts/shared/stage_ui/`. Treat the shared shell, choice group, toggle row, and
+  `stage_panels` theme tokens as the default visual and interaction system. Prefer extending
+  them over inventing a parallel panel style. The system is scoped to in-stage inspectors;
+  for dialogs or other editor workflows, reuse its visual principles only when their layout
+  and interaction model fit, and call out any exception.
+
 * **Touch & Click Target Rules:**
   * Minimum pointer hit-target: **44×44 logical pixels** (never build tiny 16px/24px buttons).
   * Control heights (buttons, dropdowns, rows) must obey `button_min_height` tokens from the theme.
@@ -56,4 +64,4 @@ Output a structured spec covering:
 * Theme & Color Tokens (Active state colors, badge accents)
 * Cursor & Canvas Feedback (Floating labels, ghost markers, trajectory lines)
 * Kid-Friendly Copy Map (Exact string replacements for all visual labels)
-"""
+"""