feat: session persistence, logout button, TURN HMAC fix; update docs

- Browser mode auto-rejoins saved network on reload (waste_last_network)
- Logout button (⏻) in sidebar clears session; optionally clears identity keypair
- TURN credentials now use HMAC-SHA1 of username (coturn use-auth-secret compatible)
- README: deploy scripts documented, session persistence section, serve-web.sh noted
- FUTURE.md: mark shipped items, add remaining work for daemon TURN + TUI rooms

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

web/src/components/Sidebar.tsx

@@ -32,7 +32,7 @@ export function Sidebar() {
     networks, activeNetworkId, activeRoom,
     connectedPeers, peerStatus,
     setActiveRoom, setActiveNetwork, messages, browseFiles, sendFileTo, adapterMode,
-    customRooms, createRoom,
+    customRooms, createRoom, logout,
   } = useWaste()
   const [addingRoom, setAddingRoom] = useState(false)
   const [newRoomName, setNewRoomName] = useState('')
@@ -54,6 +54,11 @@ export function Sidebar() {
   const displayId = localPeer?.id ?? masterId ?? ''
   const card = displayId ? makeYawCard(displayId, displayAlias) : null
 
+  function handleLogout() {
+    const clearId = window.confirm('Also clear your identity keypair? (Cannot be undone — export a backup first if you want to keep it.)')
+    logout(clearId)
+  }
+
   function openDM(peerId: string) {
     setActiveRoom(`dm:${peerId}`)
   }
@@ -64,14 +69,16 @@ export function Sidebar() {
 
   return (
     <nav className="sidebar">
-      <div
-        className="sidebar-identity"
-        title={card ?? undefined}
-        onClick={() => card && navigator.clipboard?.writeText(card)}
-        style={{ cursor: card ? 'pointer' : undefined }}
-      >
-        <span className="alias">{displayAlias || '…'}</span>
-        <span className="peer-id">{displayId.slice(0, 16).replace(/(.{4})/g, '$1 ').trim()}</span>
+      <div className="sidebar-identity">
+        <div
+          style={{ flex: 1, cursor: card ? 'pointer' : undefined }}
+          title={card ?? undefined}
+          onClick={() => card && navigator.clipboard?.writeText(card)}
+        >
+          <span className="alias">{displayAlias || '…'}</span>
+          <span className="peer-id">{displayId.slice(0, 16).replace(/(.{4})/g, '$1 ').trim()}</span>
+        </div>
+        <button className="sidebar-logout" onClick={handleLogout} title="Leave network">⏻</button>
       </div>
 
       <div className="sidebar-section">