Fix stale isSolo flag leaking into subsequent host/client sessions

After a solo session was disconnected, roomState.isSolo remained true
because clearRoomState() only clears localStorage, and solo mode has
no SocketHost whose destroy() would reset the store. Starting a hosted
room afterwards then used SocketHost._syncRoomState's spread update,
which preserved the stale isSolo flag — causing LobbyView/TimerView
to keep showing the solo badge instead of the room code.

- SocketHost._syncRoomState now explicitly sets isSolo/isSpectator to
  false so a host session can never inherit stale flags.
- Disconnect handlers in LobbyView, TimerView, and DisplayView now
  reset the roomState store alongside clearRoomState().

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: GilbN

src/lib/peer/SocketHost.js

@@ -248,6 +248,8 @@ export class SocketHost {
       ...s,
       code: this.code,
       isHost: true,
+      isSolo: false,
+      isSpectator: false,
       connectedPeers: peers,
     }))
     if (this._onPeersChange) this._onPeersChange(peers)

src/views/DisplayView.svelte

@@ -66,6 +66,7 @@
     }
     clearTimerState()
     clearRoomState()
+    roomState.set({ code: null, isHost: false, isSpectator: false, isSolo: false, connectedPeers: [] })
     currentView.set('home')
   }
 </script>

src/views/LobbyView.svelte

@@ -55,6 +55,7 @@
       window.__nsfHost = null
     }
     clearRoomState()
+    roomState.set({ code: null, isHost: false, isSpectator: false, isSolo: false, connectedPeers: [] })
     currentView.set('home')
   }
 </script>

src/views/TimerView.svelte

@@ -174,6 +174,7 @@
     }
     clearTimerState()
     clearRoomState()
+    roomState.set({ code: null, isHost: false, isSpectator: false, isSolo: false, connectedPeers: [] })
     currentView.set('home')
   }
 </script>