tsconnect: let the caller choose the PTY terminal type and modes

Upstream requests a bare "xterm" PTY with no terminal modes. Headplane
renders with Ghostty and ships a Nerd Font, so it needs xterm-256color
and sane modes for anything colour-aware on the far side.

Applied to cmd/hp_ssh/wasm_js.go by scripts/sync-tsconnect.sh.

--- a/wasm/wasm_js.go
+++ b/wasm/wasm_js.go
@@ -484,7 +484,14 @@
 	if s.pendingResizeCols != 0 {
 		cols = s.pendingResizeCols
 	}
-	err = session.RequestPty("xterm", rows, cols, ssh.TerminalModes{})
+	termType := "xterm"
+	if v := s.termConfig.Get("termType"); v.Type() == js.TypeString {
+		termType = v.String()
+	}
+	err = session.RequestPty(termType, rows, cols, ssh.TerminalModes{
+		ssh.ECHO: 1, ssh.ICANON: 1, ssh.ISIG: 1, ssh.ICRNL: 1, ssh.IUTF8: 1,
+		ssh.TTY_OP_ISPEED: 14400, ssh.TTY_OP_OSPEED: 14400,
+	})
 	if err != nil {
 		writeError("Pseudo Terminal", err)
 		return