Add 8 proposed changes and old trails analysis

Proposed changes (all with proposal, design, specs, tasks):
- app-navigation (9 tasks) — nav bars for both apps
- planner-landing-page (7 tasks) — standalone landing page
- planner-multiplayer-awareness (13 tasks) — participants, cursors, names
- changelog (13 tasks) — public changelog with "what's new"
- transactional-emails (15 tasks) — magic link + welcome emails
- planner-features (18 tasks) — no-go areas, notes, recovery, rate limits
- komoot-import (23 tasks) — Komoot tour import
- route-features (37 tasks) — sharing, multi-day, spatial, photos

Also adds docs/old-trails-analysis.md with feature analysis from the
older trails project.

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

openspec/changes/app-navigation/design.md

@@ -0,0 +1,40 @@
+## Context
+
+Navigation audit found: Journal's `/routes` and `/activities` pages are
+orphaned (no links point to them). The Planner home page has no CTA. Logout
+is only on the profile page. Users must know URLs to use the apps.
+
+## Goals / Non-Goals
+
+**Goals:**
+- Every non-API route reachable via UI navigation
+- Logged-in Journal users see: Routes, Activities, profile, logout
+- Logged-out Journal users see: login, register
+- Planner home has a clear "start planning" action
+- Keep it minimal — a thin bar, not a complex sidebar
+
+**Non-Goals:**
+- Mobile hamburger menu (responsive PR already hides sidebar — nav bar wraps naturally)
+- Breadcrumbs or nested navigation
+- Settings page (future)
+
+## Decisions
+
+### D1: Journal nav bar in root Layout
+
+Add a `<nav>` element inside `Layout` in `root.tsx`. The root loader already
+returns the user (added for Sentry context), so the nav bar can conditionally
+show authenticated vs. unauthenticated links. No new loader needed.
+
+### D2: Planner gets a CTA on home, not a nav bar
+
+The Planner is session-focused — users arrive, create a session, and work in
+it. A full nav bar would be overhead. Instead: home page gets a prominent
+"Start Planning" button linking to `/new`. Session view already has a header —
+add a small logo/home link to it.
+
+### D3: Use @trails-cool/ui for shared nav component
+
+The nav bar itself is Journal-specific (routes, activities, auth). No need
+to put it in the shared UI package — it goes directly in Journal's root.tsx
+or a colocated component.