Archive app-navigation and planner-multiplayer-awareness, sync specs

Both changes fully implemented. Sync delta specs to main:
- map-display: add Planner home page nav and cursor rendering requirements
- planner-session: add session participant awareness requirement

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

openspec/specs/map-display/spec.md

@@ -50,3 +50,25 @@ The Planner SHALL display an elevation profile chart for the current route.
 #### Scenario: Show elevation profile
 - **WHEN** a route is computed
 - **THEN** an elevation profile chart is displayed below the map showing distance vs elevation with total ascent/descent statistics
+
+### 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
+
+### 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