Canvas: toolbar fungerer, dobbeltklikk = tilpass visning, diskret seleksjon

- Toolbar-knapper (zoom, tilpass, grid, fullskjerm) blokkert av Canvas
  sin pointerdown-handler. Fikset med closest('.canvas-toolbar')-sjekk.
- Dobbeltklikk på tom flate kjører zoomToFit() for rask navigasjon.
- Seleksjon-ramme dempet: 1px rgba(accent, 0.4) i stedet for 2px solid.

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

frontend/src/lib/components/canvas/Canvas.svelte

@@ -164,6 +164,9 @@
 	// --- Pointer events ---
 	function handlePointerDown(e: PointerEvent) {
 		if (!containerEl) return;
+		// Ignore clicks on toolbar and other UI overlays
+		if ((e.target as HTMLElement).closest('.canvas-toolbar')) return;
+
 		const rect = containerEl.getBoundingClientRect();
 		const sx = e.clientX - rect.left;
 		const sy = e.clientY - rect.top;
@@ -412,6 +415,12 @@
 	onpointerdown={handlePointerDown}
 	onpointermove={handlePointerMove}
 	onpointerup={handlePointerUp}
+	ondblclick={(e) => {
+		if (!(e.target as HTMLElement).closest('[data-canvas-object-id]') &&
+			!(e.target as HTMLElement).closest('.canvas-toolbar')) {
+			zoomToFit();
+		}
+	}}
 	ontouchstart={handleTouchStart}
 	ontouchmove={handleTouchMove}
 	ontouchend={handleTouchEnd}
@@ -541,8 +550,8 @@
 	}
 
 	.canvas-object-selected {
-		outline: 2px solid #3b82f6;
-		outline-offset: 2px;
+		outline: 1px solid rgba(99, 102, 241, 0.4);
+		outline-offset: 1px;
 		border-radius: 4px;
 	}