tsconnect: type the termType option and the wasm_exec Go global

termType matches patches/tsconnect-term-type.patch. Go is declared by the
wasm_exec.js helper the Go toolchain ships, which we load ourselves rather
than through @tailscale/connect.

@@ -4,11 +4,22 @@
 /**
  * @fileoverview Type definitions for types exported by the wasm_js.go Go
  * module.
+ *
+ * Vendored from tailscale.com/cmd/tsconnect/src/types/wasm_js.d.ts; see
+ * cmd/hp_ssh/wasm_js.go for the upstream ref. Local changes live in
+ * patches/tsconnect-types.patch and are already applied here.
  */
 
 declare global {
   function newIPN(config: IPNConfig): IPN
 
+  var Go: {
+    new (): {
+      importObject: WebAssembly.Imports
+      run(instance: WebAssembly.Instance): Promise<void>
+    }
+  }
+
   interface IPN {
     run(callbacks: IPNCallbacks): void
     login(): void
@@ -22,6 +33,8 @@
         setReadFn: (readFn: (data: string) => void) => void
         rows: number
         cols: number
+        /** Defaults to "xterm" */
+        termType?: string
         /** Defaults to 5 seconds */
         timeoutSeconds?: number
         onConnectionProgress: (message: string) => void