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/planner-session/spec.md

@@ -94,3 +94,30 @@ The Planner SHALL NOT collect, store, or track any personal user data. Sessions
 #### Scenario: Anonymous session participation
 - **WHEN** a user joins a session without any account
 - **THEN** the user is assigned a random color and temporary display name with no data persisted about their identity
+
+### Requirement: Session participant awareness
+Users in a planning session SHALL see who else is present and be able to identify themselves.
+
+#### Scenario: Participant list visible
+- **WHEN** multiple users are in a session
+- **THEN** the header shows each participant's name and color
+
+#### Scenario: Host badge
+- **WHEN** a participant is the routing host
+- **THEN** their entry in the participant list shows a host indicator
+
+#### Scenario: Edit own name
+- **WHEN** a user clicks their own name in the participant list
+- **THEN** an inline text input appears to change their display name
+
+#### Scenario: Name persisted
+- **WHEN** a user changes their name
+- **THEN** the name is saved to localStorage and immediately visible to all other participants via awareness
+
+#### Scenario: Join notification
+- **WHEN** a new participant joins the session
+- **THEN** a brief toast shows "[name] joined"
+
+#### Scenario: Leave notification
+- **WHEN** a participant leaves the session
+- **THEN** a brief toast shows "[name] left"