Sync notes through GPX, Journal, and Planner roundtrip

Full notes lifecycle:
- GPX: description field in GpxData, <metadata><desc> in generate/parse
- Export: Plan GPX and Save to Journal include notes as description
- Journal: updateRoute extracts description from GPX, stores on route
- Reimport: Edit in Planner passes notes via URL params → Yjs Y.Text
- Drop import: GPX with <desc> restores notes in session

Spec updated: session-notes gains GPX export, Journal sync, and
reimport requirements.

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

packages/gpx/src/generate.ts

@@ -10,6 +10,7 @@ export interface NoGoArea {
 
 export function generateGpx(options: {
   name?: string;
+  description?: string;
   waypoints?: Waypoint[];
   tracks?: TrackPoint[][];
   noGoAreas?: NoGoArea[];
@@ -25,8 +26,11 @@ export function generateGpx(options: {
       ">",
   ];
 
-  if (options.name) {
-    lines.push("  <metadata>", `    <name>${escapeXml(options.name)}</name>`, "  </metadata>");
+  if (options.name || options.description) {
+    lines.push("  <metadata>");
+    if (options.name) lines.push(`    <name>${escapeXml(options.name)}</name>`);
+    if (options.description) lines.push(`    <desc>${escapeXml(options.description)}</desc>`);
+    lines.push("  </metadata>");
   }
 
   if (options.waypoints) {

packages/gpx/src/parse.ts

@@ -44,12 +44,13 @@ function parseGpxWithParser(parser: DOMParser, xml: string): GpxData {
   }
 
   const name = doc.querySelector("metadata > name")?.textContent ?? undefined;
+  const description = doc.querySelector("metadata > desc")?.textContent ?? undefined;
   const waypoints = parseWaypoints(doc);
   const tracks = parseTracks(doc);
   const noGoAreas = parseNoGoAreas(doc);
   const { totalDistance, ...elevation } = computeElevation(tracks);
 
-  return { name, waypoints, tracks, noGoAreas, distance: totalDistance, elevation };
+  return { name, description, waypoints, tracks, noGoAreas, distance: totalDistance, elevation };
 }
 
 function parseWaypoints(doc: Document): Waypoint[] {

packages/gpx/src/types.ts

@@ -20,6 +20,7 @@ export interface NoGoArea {
 
 export interface GpxData {
   name?: string;
+  description?: string;
   waypoints: Waypoint[];
   tracks: TrackPoint[][];
   noGoAreas: NoGoArea[];