Fix all OpenSpec validation failures (36/36 passing)

- Add ## Purpose sections and convert delta headers to ## Requirements
  on all 25 specs
- Add SHALL keywords to requirements missing them (gpx-import,
  planner-session, planner-journal-handoff)
- Convert prose GPX format section to proper scenarios (no-go-areas)
- Create specs/ delta files for 7 changes that were missing them
  (activity-photos, local-dev-stack, multi-day-routes, route-discovery,
  route-sharing, visual-redesign, waypoint-notes)

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

openspec/changes/route-discovery/specs/route-discovery/spec.md

@@ -0,0 +1,28 @@
+## ADDED Requirements
+
+### Requirement: Map-based route exploration
+The Journal SHALL provide an explore page with a full-page map for browsing public routes by location.
+
+#### Scenario: Browse public routes
+- **WHEN** a user visits `/routes/explore`
+- **THEN** a full-page Leaflet map is displayed
+- **AND** public routes within the current viewport are shown as clickable polylines
+
+#### Scenario: Route popup
+- **WHEN** a user clicks a route polyline on the explore map
+- **THEN** a popup shows the route name, distance, elevation gain, author, and a link to the detail page
+
+### Requirement: Bounding box spatial query
+The Journal SHALL provide an API endpoint for querying public routes by map viewport bounds.
+
+#### Scenario: Viewport query
+- **WHEN** the map viewport changes
+- **THEN** the client requests routes intersecting the current bounds via PostGIS `ST_Intersects`
+- **AND** results are limited to 50 routes with simplified geometries
+
+### Requirement: Spatial index
+The routes table SHALL have a GiST index on the geometry column for fast bounding box queries.
+
+#### Scenario: Index exists
+- **WHEN** the database is set up
+- **THEN** a GiST index on `journal.routes.geom` supports efficient spatial queries