Add split export: Export Route vs Export Plan

Split button with default "Export GPX" (track only) and dropdown:
- Export Route: clean track for use in any app
- Export Plan: track + waypoints + no-go areas in GPX extensions
  (trails:planning namespace) for reimporting into the planner

Also:
- Add no-go area serialization to generateGpx (GPX extensions)
- Parse no-go areas from GPX extensions on import
- Initialize no-go areas in Yjs session from imported GPX
- Save to Journal now exports track only (consistent with Export Route)

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

apps/planner/app/routes/api.sessions.ts

@@ -1,6 +1,6 @@
 import { data } from "react-router";
 import type { Route } from "./+types/api.sessions";
-import { createSession, listSessions } from "~/lib/sessions";
+import { createSession, listSessions, initializeSessionWithNoGoAreas } from "~/lib/sessions";
 import { parseGpxAsync, extractWaypoints } from "@trails-cool/gpx";
 import { withDb } from "@trails-cool/db";
 
@@ -25,6 +25,9 @@ export async function action({ request }: Route.ActionArgs) {
         const gpxData = await parseGpxAsync(gpx);
         const wps = extractWaypoints(gpxData);
         if (wps.length > 0) initialWaypoints = wps;
+        if (gpxData.noGoAreas.length > 0) {
+          initializeSessionWithNoGoAreas(session.id, gpxData.noGoAreas);
+        }
       } catch {
         // Continue with empty session if GPX is invalid
       }

apps/planner/app/routes/new.tsx

@@ -1,6 +1,6 @@
 import { redirect, data } from "react-router";
 import type { Route } from "./+types/new";
-import { createSession, initializeSessionWithWaypoints } from "~/lib/sessions";
+import { createSession, initializeSessionWithWaypoints, initializeSessionWithNoGoAreas } from "~/lib/sessions";
 import { parseGpxAsync, extractWaypoints } from "@trails-cool/gpx";
 import { checkRateLimit } from "~/lib/rate-limit";
 
@@ -37,6 +37,9 @@ export async function loader({ request }: Route.LoaderArgs) {
       const gpx = decodeURIComponent(gpxEncoded);
       const gpxData = await parseGpxAsync(gpx);
       initializeSessionWithWaypoints(session.id, extractWaypoints(gpxData));
+      if (gpxData.noGoAreas.length > 0) {
+        initializeSessionWithNoGoAreas(session.id, gpxData.noGoAreas);
+      }
     } catch {
       // Continue with empty session if GPX is invalid
     }