docs: update project docs for v1.0.0 release

- PROJECT.md: Add peer sync feature description and architecture
- ROADMAP.md: Update to v1.0.0, mark peer sync complete
- TASKS.md: Add peer sync completed tasks, update sprint
- TODO.md: Add multi-scanner section, mark items done
- CHANGELOG.md: Add v0.4.0 (HA) and v1.0.0 (peer sync) entries

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -6,6 +6,43 @@ Format based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ---
 
+## [1.0.0] - 2026-02-01
+
+### Added
+
+- **Multi-Scanner Peer Sync** - Multiple scanner instances share device metadata
+  - Peer registration API (`/api/peers/register`)
+  - Bidirectional sync (`/api/sync/devices`)
+  - Background sync thread (30s default interval)
+  - Automatic mutual registration between peers
+- **Source scanner tracking** - Synced devices retain original detector info
+  - Devices positioned relative to detecting scanner, not local scanner
+  - Moving local scanner doesn't affect synced device positions
+- **Peer scanner markers** - Show peer scanners on 3D map (cyan icons)
+- Scanner identity configuration (id, name, floor, position)
+- Timestamp-based conflict resolution for sync
+
+### Changed
+
+- Device positions now use peer's current position (live lookup)
+- Popup shows "Source: <scanner>" for remotely-synced devices
+
+---
+
+## [0.4.0] - 2026-02-01
+
+### Added
+
+- **Home Assistant Integration** - Webhook-based presence tracking
+  - Scan results webhook (`rf_mapper_scan`)
+  - New device alerts webhook (`rf_mapper_new_device`)
+  - Device departure webhook (`rf_mapper_device_gone`)
+  - Configurable timeout for departure detection
+- Scanner identity (id, name, floor) in webhooks
+- Absence checker background thread
+
+---
+
 ## [0.3.0] - 2026-02-01
 
 ### Added