Metro map interaction redesign: fit-to-view zoom, grid, branch handles, custom tracks

Phase 1 — Fit-to-view zoom:
- computeFitTransform() calculates bounding box and scales to fit all nodes
- Replaces hardcoded scale=1 reset in animateZoomReset() and initCanvas()
- Dim 1 no longer appears tiny after zooming out from dim 2

Phase 2 — Grid system:
- Shared gridConstants.js (GRID=50, GRID_STEP_X=200, GRID_STEP_Y=150)
- MapDataService snapToGrid() aligns all node positions server-side
- Canvas renders subtle grid lines (shown on interaction only, with fade)
- Line highlighting support via setHighlightedLine() for FAB hover

Phase 3 — Branch handles:
- Hover any station node → 3 "+" handles appear (0°/45°/315°)
- 0° extends the current line, 45°/315° fork to create new branch
- Ghost preview (dashed line + circle) on handle hover
- Handles only show at unoccupied grid positions
- Grid fades in during handle interaction, fades out after

Phase 4 — Custom tracks database:
- metro_lines table (project_id, naam, color, type, order)
- metro_nodes table (metro_line_id, naam, status, x, y, order)
- MetroLine + MetroNode models, controllers, routes
- Project.metroLines() relationship added

Phase 5+6 — FAB redesign + MetroMap wiring:
- FAB shows "Nieuw thema (lijn)" at root, "Nieuwe lijn" in project dim
- Track creation modal with retro-styled form
- MetroMap handles create-node events from branch handles
- Extend (0°) opens commitment/document form, fork opens track form
- Canvas context menu replaced with "hover to branch" hint

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

routes/web.php

@@ -3,6 +3,8 @@
 use App\Http\Controllers\CommitmentController;
 use App\Http\Controllers\DocumentController;
 use App\Http\Controllers\MapController;
+use App\Http\Controllers\MetroLineController;
+use App\Http\Controllers\MetroNodeController;
 use App\Http\Controllers\ProjectController;
 use App\Http\Controllers\ThemaController;
 use Illuminate\Support\Facades\Route;
@@ -48,6 +50,15 @@ Route::middleware(['auth', 'verified'])->group(function () {
     Route::get('/documents/{document}/download', [DocumentController::class, 'download'])->name('documents.download');
     Route::delete('/documents/{document}', [DocumentController::class, 'destroy'])->name('documents.destroy');
 
+    // Metro Lines
+    Route::post('/metro-lines', [MetroLineController::class, 'store'])->name('metro-lines.store');
+    Route::delete('/metro-lines/{metroLine}', [MetroLineController::class, 'destroy'])->name('metro-lines.destroy');
+
+    // Metro Nodes
+    Route::post('/metro-nodes', [MetroNodeController::class, 'store'])->name('metro-nodes.store');
+    Route::put('/metro-nodes/{metroNode}', [MetroNodeController::class, 'update'])->name('metro-nodes.update');
+    Route::delete('/metro-nodes/{metroNode}', [MetroNodeController::class, 'destroy'])->name('metro-nodes.destroy');
+
     // Dashboard (redirects to map)
     Route::get('/dashboard', fn () => redirect('/map'))->name('dashboard');
 });