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/planner-multiplayer-awareness/specs/map-display/spec.md

@@ -0,0 +1,12 @@
+## MODIFIED Requirements
+
+### Requirement: Map cursor rendering
+Other participants' cursors on the map SHALL be clearly visible with proper styling.
+
+#### Scenario: Cursor appearance
+- **WHEN** another participant moves their mouse on the map
+- **THEN** a colored pointer icon with their name tag appears at the cursor position
+
+#### Scenario: Cursor does not obscure map controls
+- **WHEN** cursors are rendered
+- **THEN** they appear below map controls (zoom, layer switcher) in z-index