feat: Add presence heartbeat for Matrix online status

- matrix-gateway: POST /internal/matrix/presence/online endpoint
- usePresenceHeartbeat hook with activity tracking
- Auto away after 5 min inactivity
- Offline on page close/visibility change
- Integrated in MatrixChatRoom component

node-network-app/node_modules/hasown/.nycrc

@@ -0,0 +1,13 @@
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+	"reporter": ["text-summary", "text", "html", "json"],
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+	"branches": 76.06,
+	"exclude": [
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+}