Add peer-to-peer file transfer in browser mode

Implements both pull (browse & download from a shared folder) and push
(send a file directly to a peer) using the yaw2 file protocol over WebRTC
DataChannels.

- PeerConn: handle browse/files/get/file-offer/file-accept/file-done
  control messages; stream files in 64KB chunks over f:xid binary
  DataChannels; auto-accept incoming offers (push and pull)
- PeerConn.sendFilePush(): initiate an outbound file transfer without
  requiring the peer to browse first
- BrowserAdapter: sharedFiles map, setSharedFiles(), requestBrowse(),
  requestGet(), sendFileTo() — propagates share map to all active peers
- Store: activeFilePeer, setActiveFilePeer, setSharedFiles, browseFiles,
  sendFileTo; file_complete handler triggers browser download automatically
- FileBrowser component: third-column panel listing a peer's shared files
  with name, size, and a download button
- FolderPicker component: webkitdirectory input in the sidebar (browser
  mode only) for selecting a local folder to share
- Sidebar: 📎 send-file button on peer rows (hover) with inline file picker
- App.tsx: use browser mode when WASTE_CONFIG.signalURL is set, even on
  localhost — allows testing browser mode via npm run dev with config.js
- deploy-daemon.sh: kill existing daemon before scp to avoid upload failure
  when the binary is locked; remove duplicate kill block in restart step

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

web/src/store/index.ts

@@ -43,6 +43,9 @@ interface WasteState {
   // identity backup export result (cleared when consumed)
   exportedBackup: string | null
 
+  // file browser state
+  activeFilePeer: string | null
+
   // actions
   connect: (url: string) => void
   connectBrowser: () => void
@@ -50,6 +53,10 @@ interface WasteState {
   send: (msg: IpcMessage) => void
   setActiveNetwork: (id: string) => void
   setActiveRoom: (room: string) => void
+  setActiveFilePeer: (peerId: string | null) => void
+  setSharedFiles: (files: Map<string, File>) => void
+  browseFiles: (peerId: string) => void
+  sendFileTo: (peerId: string, file: File) => void
   handleEvent: (msg: IpcMessage) => void
 }
 
@@ -68,6 +75,7 @@ export const useWaste = create<WasteState>((set, get) => ({
   fileLists: {},
   exportedBackup: null,
   peerStatus: {},
+  activeFilePeer: null,
 
   connect(url: string) {
     const adapter = new DaemonAdapter(url)
@@ -104,6 +112,30 @@ export const useWaste = create<WasteState>((set, get) => ({
     set({ activeRoom: room })
   },
 
+  setActiveFilePeer(peerId) {
+    set({ activeFilePeer: peerId })
+  },
+
+  setSharedFiles(files) {
+    const a = get().adapter
+    if (a instanceof BrowserAdapter) a.setSharedFiles(files)
+  },
+
+  sendFileTo(peerId, file) {
+    const a = get().adapter
+    if (a instanceof BrowserAdapter) a.sendFileTo(peerId, file)
+  },
+
+  browseFiles(peerId) {
+    const a = get().adapter
+    if (a instanceof BrowserAdapter) {
+      a.requestBrowse(peerId)
+    } else {
+      get().send({ type: 'get_file_list', peer_id: peerId as unknown as import('../types').PeerID })
+    }
+    set({ activeFilePeer: peerId })
+  },
+
   handleEvent(msg) {
     switch (msg.type) {
       case 'state_snapshot': {
@@ -215,6 +247,16 @@ export const useWaste = create<WasteState>((set, get) => ({
         }
         break
       }
+      case 'file_complete': {
+        // path holds the blob URL, offer.name holds the filename
+        if (msg.path && msg.offer?.name) {
+          const a = document.createElement('a')
+          a.href = msg.path
+          a.download = msg.offer.name
+          a.click()
+        }
+        break
+      }
     }
   },
 }))