Recursive zoom dimensions with smooth transitions

MetroCanvas rewrite:
- Dimension stack: every node can contain children forming a sub-metro-map
- Zoom-triggered transitions: scroll-zoom near a node gradually cross-fades
  parent dimension out and child dimension in (threshold 2.5x, range 1.5x)
- Zoom out past 0.5x transitions back to parent dimension
- Right-click context menu: "New node here" on canvas, "Edit/Add child/Delete" on stations
- Depth indicator HUD with back button
- Transition progress bar during cross-fade
- Nodes with children get dashed ring + glow indicator

Backend:
- MapDataService now includes children data inline per project node
- Each project's children contain lifecycle phases, commitments, documents as sub-map
- New API endpoint: GET /api/map/node/{type}/{id}/children for lazy loading
- Consistent data structure: every node has children field (null = leaf)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

routes/web.php

@@ -20,6 +20,7 @@ Route::middleware(['auth', 'verified'])->group(function () {
     Route::prefix('api')->group(function () {
         Route::get('/map/strategy', [MapController::class, 'apiStrategy'])->name('api.map.strategy');
         Route::get('/map/project/{project}', [MapController::class, 'apiProject'])->name('api.map.project');
+        Route::get('/map/node/{type}/{id}/children', [MapController::class, 'apiNodeChildren'])->name('api.map.node.children');
     });
 
     // Projects