feat(prefs): export/import Saved Points (merge + dedupe by id) in Preferences dialog

src/lib/components/MapView.svelte

@@ -7,7 +7,7 @@
 	import DirectionsPanel from '$lib/components/DirectionsPanel.svelte';
 	import { prefs } from '$lib/prefs';
 	import type { RouteGraph, AvoidRule, RouteResult } from '$lib/routing';
-	import { savedPoints, addSavedPoint, removeSavedPoint, type SavedPoint } from '$lib/savedPoints';
+	import { savedPoints, addSavedPoint, exportSavedPoints, importSavedPoints, type SavedPoint } from '$lib/savedPoints';
 
 	type FeatureCollection = {
 		type: string;
@@ -271,6 +271,43 @@
 		savedPointsVisible = !savedPointsVisible;
 		void drawSavedPoints();
 	}
+	let importMsg = $state<string | null>(null);
+
+	// Download the current saved points as JSON.
+	function exportSavedPointsToFile() {
+		const json = exportSavedPoints();
+		const blob = new Blob([json], { type: 'application/json' });
+		const url = URL.createObjectURL(blob);
+		const a = document.createElement('a');
+		a.href = url;
+		a.download = `navigator-saved-points-${new Date().toISOString().slice(0, 10)}.json`;
+		document.body.appendChild(a);
+		a.click();
+		a.remove();
+		URL.revokeObjectURL(url);
+	}
+
+	// Read a selected file and merge its saved points into the store.
+	function importSavedPointsFromFile(file: File | null) {
+		importMsg = null;
+		if (!file) return;
+		if (file.type && file.type !== 'application/json' && !file.name.endsWith('.json')) {
+			importMsg = 'Please choose a .json file.';
+			return;
+		}
+		const reader = new FileReader();
+		reader.onload = () => {
+			try {
+				const { added, skipped } = importSavedPoints(String(reader.result));
+				importMsg = `Imported ${added} point${added === 1 ? '' : 's'}${skipped ? `, skipped ${skipped} existing` : ''}.`;
+			} catch (e) {
+				importMsg = e instanceof Error ? e.message : 'Import failed.';
+			}
+		};
+		reader.onerror = () => { importMsg = 'Could not read the file.'; };
+		reader.readAsText(file);
+	}
+
 	function setSavedPointAsOrigin(p: SavedPoint) {
 		setOrigin(p.lat, p.lon, p.label || 'Saved point');
 	}
@@ -569,6 +606,21 @@
 					</select>
 				</div>
 				<div class="pref-hint">Distances use m/ft under a km/mile, otherwise km/mi. Saved to this browser (localStorage).</div>
+
+				<div class="pref-rule"></div>
+				<div class="pref-title small">Saved Points ({savedPointsList.length})</div>
+				<div class="pref-row">
+					<span class="pref-label">Back up / restore your saved points</span>
+				</div>
+				<div class="pref-btns">
+					<button class="pref-small-btn" onclick={() => exportSavedPointsToFile()} disabled={!savedPointsList.length}>Export</button>
+					<label class="pref-file">
+						Import…
+						<input type="file" accept="application/json,.json" hidden onchange={(e) => importSavedPointsFromFile((e.target as HTMLInputElement).files?.[0] ?? null)} />
+					</label>
+				</div>
+				{#if importMsg}<div class="pref-import-msg">{importMsg}</div>{/if}
+
 				<button class="pref-close" onclick={() => (showPrefs = false)}>Done</button>
 			</div>
 		</div>
@@ -685,6 +737,16 @@
 		background: #0f172a; color: #fff; font-weight: 600; cursor: pointer; font-size: 0.85rem;
 	}
 	.pref-close:hover { background: #1e293b; }
+	.pref-rule { border-top: 1px solid #e2e8f0; margin: 14px 0 8px; }
+	.pref-title.small { font-size: 0.82rem; margin-bottom: 6px; }
+	.pref-btns { display: flex; gap: 8px; margin-top: 4px; }
+	.pref-small-btn, .pref-file {
+		display: inline-flex; align-items: center; padding: 6px 12px; border-radius: 6px;
+		border: 1px solid #cbd5e1; background: #fff; cursor: pointer; font-size: 0.78rem; color: #0f172a;
+	}
+	.pref-small-btn:hover, .pref-file:hover { background: #f1f5f9; }
+	.pref-small-btn:disabled { opacity: .5; cursor: default; }
+	.pref-import-msg { font-size: 0.72rem; color: #475569; margin-top: 8px; }
 	/* saved points pin */
 	:global(.saved-pin-wrap) { background: transparent; border: none; }
 	:global(.saved-pin) { width: 0; height: 0; border: 10px solid transparent; border-bottom: 0; border-left-color: #8b5cf6; }