fix: update engine imports after moving to /src/engine

Migrate 268+ file references from /engine to /src/engine across and 128 across PR *.md files
JavaScript, HTML, and documentation files. Add reusable PowerShell
migration script. All tests passing.

Author: ToolboxAid

README.md

@@ -24,6 +24,6 @@ This repository is a docs-first game/runtime workspace with a stable engine laye
 - `docs/archive/`: archived dev-ops notes and generated reports
 
 ## Runtime Boundary Reminder
-- Engine code remains in `engine/`.
+- Engine code remains in `src/engine/`.
 - Advanced composable architecture remains in `src/advanced/`.
 - Tools/samples/games consume public contracts and should not bypass engine boundaries.

docs/architecture/README.md

@@ -21,7 +21,7 @@ README.md
 - `engine-scene-transitions.md`
 
 ## Layer Model
-- `engine/`: stable foundational runtime systems
+- `src/engine/`: stable foundational runtime systems
 - `src/advanced/`: composable advanced architecture layer
 - `samples/`: usage demonstrations
 - `games/`: consumer implementations

docs/architecture/engine-api-boundary.md

@@ -6,13 +6,13 @@ engine-api-boundary.md
 # Engine API Boundary
 
 ## Boundary Rules
-- `engine/` must not depend on `src/advanced/`.
+- `src/engine/` must not depend on `src/advanced/`.
 - Advanced modules in `src/advanced/` must use public engine contracts only.
 - Samples, tools, and games must not patch engine internals for project-specific behavior unless explicitly approved in PR scope.
 
 ## State Ownership
 - Authoritative advanced state belongs in `src/advanced/state/`.
-- Foundational reusable state/runtime primitives remain in `engine/`.
+- Foundational reusable state/runtime primitives remain in `src/engine/`.
 
 ## Docs and Process Boundary
 - Architecture decisions are documented in `docs/architecture/` and `docs/pr/`.

docs/architecture/engine-render.md

@@ -13,9 +13,9 @@ Scene -> Renderer -> CanvasRenderer -> CanvasRenderingContext2D
 
 ## Core files
 
-- `engine/render/Renderer.js`
-- `engine/render/CanvasRenderer.js`
-- `engine/core/Engine.js`
+- `src/engine/render/Renderer.js`
+- `src/engine/render/CanvasRenderer.js`
+- `src/engine/core/Engine.js`
 
 ## Responsibilities
 

docs/architecture/engine-scene-transitions.md

@@ -8,9 +8,9 @@ The transition layer exists to own scene handoff effects so that individual scen
 
 ## Added files
 
-- `engine/scenes/SceneTransition.js`
-- `engine/scenes/TransitionScene.js`
-- `engine/scenes/index.js`
+- `src/engine/scenes/SceneTransition.js`
+- `src/engine/scenes/TransitionScene.js`
+- `src/engine/scenes/index.js`
 
 ## Responsibilities
 

docs/architecture/repo-operating-model.md

@@ -20,7 +20,7 @@ This document captures the durable operating model for how this repository is or
 - `docs/pr/` is the historical PR and architecture trail and must remain intact.
 
 ## Layer Boundaries
-- `engine/` owns foundational reusable runtime systems.
+- `src/engine/` owns foundational reusable runtime systems.
 - `src/advanced/` owns composable higher-level architecture patterns.
 - `samples/` demonstrates usage patterns and should not become the source of reusable runtime logic.
 - `games/` consumes public contracts; it should not bypass engine boundaries.

docs/archive/dev-ops/DOC_CLEANUP_AND_UPDATE_AUDIT.md

@@ -106,7 +106,7 @@ This needs explicit updates for:
 - `src/advanced/state/`
 - `docs/dev/reports/`
 - current purpose of `games/`, `tools/`, `samples/`
-- distinction between `engine/` and `src/advanced/`
+- distinction between `src/engine/` and `src/advanced/`
 
 ### 4. `docs/getting-started.md`
 Update onboarding to current reality:
@@ -126,17 +126,17 @@ Update review checklist to include:
 
 ### 6. `docs/architecture/README.md`
 Update to include the current layered model:
-- `engine/` = stable foundational systems
+- `src/engine/` = stable foundational systems
 - `src/advanced/` = composable optional architecture layer
 - `games/` = primary consumers
 - `tools/` = optional consumers
 - `samples/` = demonstration only
 
 ### 7. `docs/architecture/engine-api-boundary.md`
 Update to explicitly state:
-- authoritative state belongs in `src/advanced/state/`, not `engine/state/`
+- authoritative state belongs in `src/advanced/state/`, not `src/engine/state/`
 - engine must not import advanced systems
-- reusable + foundational goes to `engine/`
+- reusable + foundational goes to `src/engine/`
 - reusable + composable goes to `src/advanced/`
 
 ### 8. `docs/dev/README.md`

docs/archive/pr/legacy-pr-history/APPLY_PR_DEBUG_SURFACES_INSPECTORS.md

@@ -26,7 +26,7 @@ Included contracts:
 - No runtime mutation APIs
 - No unrelated engine changes
 - No breaking sample behavior
-- Preserve engine/runtime separation
+- Preserve src/engine/runtime separation
 - Debug surfaces remain optional
 
 ## Validation Requirements

docs/archive/pr/legacy-pr-history/APPLY_PR_DEBUG_SURFACES_NETWORK_PROMOTION.md

@@ -16,9 +16,9 @@ Apply the approved network promotion by introducing shared reusable network debu
 - no combo-key behavior changes
 
 ## Ordered Apply Sequence
-1. Add `engine/debug/network` shared modules (shared/provider/panel/command/bootstrap).
-2. Add read-only dashboard and diagnostics helpers under `engine/debug/network`.
-3. Export shared network layer through `engine/debug/index.js`.
+1. Add `src/engine/debug/network` shared modules (shared/provider/panel/command/bootstrap).
+2. Add read-only dashboard and diagnostics helpers under `src/engine/debug/network`.
+3. Export shared network layer through `src/engine/debug/index.js`.
 4. Rebind Sample A/B/C debug plugin factories through shared network bootstrap.
 5. Run targeted import and smoke checks.
 
@@ -31,6 +31,6 @@ Apply the approved network promotion by introducing shared reusable network debu
 
 ## Rollback
 If promotion causes regressions:
-- revert `engine/debug/network` additions
+- revert `src/engine/debug/network` additions
 - restore direct plugin object construction in sample debug plugin files
 - keep sample-level behavior as pre-promotion baseline

docs/archive/pr/legacy-pr-history/APPLY_PR_DEBUG_SURFACES_PROMOTION.md

@@ -4,7 +4,7 @@
 Apply the approved extraction/relocation plan for debug surfaces with no feature expansion and minimal engine-core changes.
 
 ## Apply Scope
-- relocate proven reusable debug systems into `engine/debug`
+- relocate proven reusable debug systems into `src/engine/debug`
 - keep engine-core changes limited to debug contracts/hooks
 - preserve local ownership for sample-specific panels/providers/commands
 - preserve `MultiSystemDemoScene.js` as proving integration
@@ -32,4 +32,4 @@ Apply the approved extraction/relocation plan for debug surfaces with no feature
 - no unrelated files or systems changed
 
 ## Expected Outcome
-Debug surfaces are promoted out of `tools/dev` into shared `engine/debug` structure while engine-core remains minimal and local sample integrations stay local.
+Debug surfaces are promoted out of `tools/dev` into shared `src/engine/debug` structure while engine-core remains minimal and local sample integrations stay local.