Break up route-features into focused specs, add new changes

Archive the monolithic route-features spec and replace with 9 focused
OpenSpec changes: multi-day-routes, waypoint-notes (with POI snapping),
undo-redo, local-dev-stack, route-sharing, route-discovery,
activity-photos, osm-overlays, plus the existing changelog and
komoot-import.

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

openspec/changes/route-sharing/proposal.md

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+## Why
+
+Routes in the Journal are currently invisible to everyone except the owner. There
+is no way to make a route public, share it with a specific person, or fork
+someone else's route into your own collection. The architecture doc specifies
+visibility levels, a permission matrix, and forking for Phase 2, and the original
+`route-features` spec bundled these with spatial search, multi-day routes, and
+photos. This change breaks out the sharing and permissions scope into a focused,
+independent unit of work.
+
+Without visibility and sharing, routes are just private GPX storage. Users cannot
+show a planned bikepacking route to a friend, let a co-planner view the latest
+version in the Journal, or build on someone else's published route. This is the
+minimum social layer needed before federation makes routes visible across
+instances.
+
+## What Changes
+
+- **Route visibility**: `private` (default) and `public` on routes and
+  activities. Public routes are viewable by anyone with the link. Private routes
+  are owner-only.
+- **Route sharing**: Owners can share a route with specific users at `view` or
+  `edit` permission level. Shared users see the route in their collection and can
+  act according to their permission.
+- **Route forking**: Logged-in users can fork any public route, copying the route
+  metadata and latest GPX into their own collection with a `forkedFromId` link
+  back to the original.
+- **Contributor tracking**: When the Planner saves back to the Journal via JWT
+  callback, the contributor's identity is recorded on the route version. The
+  route detail page shows who contributed to each version.
+
+These are all Journal-side changes (database schema, server logic, and UI). No
+Planner changes are needed.
+
+## Capabilities
+
+### New Capabilities
+
+- `route-sharing`: Visibility levels (private/public), per-user sharing with
+  view/edit permissions, share dialog with user search
+- `route-forking`: Copy public routes into own collection with provenance link
+
+### Modified Capabilities
+
+- `route-management`: Visibility toggle on routes and activities, permission
+  checks on all route access, contributor display
+- `planner-callback`: JWT callback records contributor identity on route versions
+
+## Non-Goals
+
+- **Granular permissions beyond view/edit**: No "edit waypoints but not
+  description" or "view but not export GPX". Two levels are enough.
+- **Team or organization sharing**: No group-level permissions. Share with
+  individual users only.
+- **ActivityPub federation of shares**: Sharing is local to the instance for now.
+  Cross-instance sharing comes with the federation change.
+- **Followers-only visibility**: Only private and public for now. A
+  followers-only level can be added when the follow system exists.
+- **Spatial search / explore page**: Broken out as a separate change. Public
+  routes are a prerequisite; discovery is not.
+
+## Impact
+
+- **Database**: New `visibility` enum column on `journal.routes` and
+  `journal.activities`. New `journal.route_shares` table. New `contributors`
+  text array on `journal.route_versions`. New `forkedFromId` column on
+  `journal.routes`.
+- **Server logic**: New `permissions.server.ts` module with `canView` and
+  `canEdit` functions. Route loaders and list queries updated to respect
+  permissions.
+- **UI**: Visibility toggle on route detail/edit page. Share dialog modal with
+  user search. Fork button on public routes. "Forked from" link. Contributor
+  list on route detail.
+- **Privacy**: Privacy manifest updated to document visibility and sharing
+  behavior.
+- **i18n**: New translation keys for visibility, sharing, forking, contributors
+  (en + de).