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/specs/map-display/spec.md

@@ -0,0 +1,12 @@
+## MODIFIED Requirements
+
+### Requirement: Planner home page
+The Planner home page SHALL provide a clear call-to-action to create a new planning session and a link back to the home page from within sessions.
+
+#### Scenario: Home page CTA
+- **WHEN** a user visits the Planner home page
+- **THEN** a prominent "Start Planning" button is visible that links to `/new`
+
+#### Scenario: Session home link
+- **WHEN** a user is in a planning session
+- **THEN** the header contains a link back to the Planner home page