fix(desktop): route fetch + WebSocket through native Tauri plugins (mixed-content)

Fixing VITE_API_BASE got login to build a correct absolute URL, but it still
failed with WebKit's generic "Load failed" — WebKitGTK treats tauri://localhost
as a secure origin, so http://127.0.0.1:3000 (and ws://) from inside it is
blocked as mixed content, a WebKit limitation CSP's connect-src can't override.

Added tauri-plugin-http (genuine fetch() drop-in, wired via a new
platformFetch() in origin.ts, used by api.ts + logger.ts) and
tauri-plugin-websocket (not a drop-in — adapted behind a native-WebSocket-
shaped interface in the new platform-ws.ts so use-live-feed.ts needed no
changes). Both route through Tauri's Rust side instead of the webview's own
fetch/WebSocket. Capabilities scoped to 127.0.0.1:3000/localhost:3000, matching
the existing CSP allowlist.

apps/web/src/lib/use-live-feed.ts

@@ -4,6 +4,7 @@ import type { DeviceStatus, LedgerEvent, Occupancy } from "../api.js";
 import { qk } from "./query.js";
 import { useLiveStore, type LaneStatus, type LanePresence } from "./live-store.js";
 import { wsUrl } from "./origin.js";
+import { createPlatformSocket, type PlatformSocket } from "./platform-ws.js";
 
 // Booth WebSocket client. Opens ONE socket to /api/ws and turns server pushes into
 // (a) live-store updates for the ticker/occupancy and (b) Query cache invalidations
@@ -36,7 +37,7 @@ export function useLiveFeed(enabled: boolean = true): void {
     useLiveStore();
   // Hold the socket + reconnect timer across renders; guard against StrictMode
   // double-invoke and unmount.
-  const sockRef = useRef<WebSocket | null>(null);
+  const sockRef = useRef<PlatformSocket | null>(null);
   const retryRef = useRef(0);
   const closedRef = useRef(false);
 
@@ -50,7 +51,7 @@ export function useLiveFeed(enabled: boolean = true): void {
     const connect = () => {
       if (closedRef.current) return;
       setStatus(retryRef.current === 0 ? "connecting" : "connecting");
-      const sock = new WebSocket(wsUrl("/api/ws"));
+      const sock = createPlatformSocket(wsUrl("/api/ws"));
       sockRef.current = sock;
 
       sock.onopen = () => {