feat(editor): F4.6b the command line on a computer's desktop

A new oracle, TerminalWindowRun, types into Java's own command line
window: the window writes each line after its prompt, takes a blank
line, cls, reset and exit itself, keeps the lines for the arrow keys,
and keeps its text, history and working directory over a stop and a
start.

The room now holds a command line window per computer for everyone
(TerminalWindow), kept over stops; the protocol carries its lines and
the one way to read them (terminalScreen); the core goes on in the
working directory of the run before (continueIn). The desktop opens
programs in Java's frame, and the command line works with keyboard and
finger: grey on black, the prompt hidden while a command runs, history,
chips for the commands, Ctrl+C. The room's failure is now tested in the
browser.

Fixed: the room handed the engine the wall clock with fractions of a
millisecond, and a ping hung after its first timeout. The engine and
the room count whole milliseconds, as Java's clock does.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/editor/src/desktop/desktop.css

@@ -183,3 +183,115 @@
   width: 18px;
   height: 18px;
 }
+
+/* A program's window over the desktop (GUIApplicationWindow): Java's dark
+ * grey title bar of 30 pixels with the icon at 16. */
+.program-window {
+  position: absolute;
+  inset: 0;
+  display: flex;
+  flex-direction: column;
+  background: #ffffff;
+}
+
+.program-titlebar {
+  display: grid;
+  grid-template-columns: 30px 1fr 30px;
+  align-items: center;
+  height: 30px;
+  flex: none;
+  background: rgb(64 64 64);
+}
+
+.program-titlebar img {
+  justify-self: center;
+  width: 16px;
+  height: 16px;
+}
+
+.program-titlebar h3 {
+  margin: 0;
+  text-align: center;
+  font: 13px Dialog, sans-serif;
+  color: rgb(225 225 225);
+}
+
+.program-content {
+  position: relative;
+  flex: 1;
+  min-height: 0;
+  display: flex;
+  flex-direction: column;
+}
+
+/* The command line (GUIApplicationTerminalWindow): grey on black, the input
+ * line right after the text in the same scrolling area. 16 pixels in the
+ * input: Safari on the iPad zooms into smaller fields. */
+.terminal {
+  flex: 1;
+  min-height: 0;
+  display: flex;
+  flex-direction: column;
+  background: #000000;
+}
+
+.terminal-screen {
+  flex: 1;
+  min-height: 0;
+  overflow-y: auto;
+  padding: 5px 5px 5px;
+  color: rgb(222 222 222);
+  font: 14px ui-monospace, Menlo, Consolas, 'Courier New', monospace;
+  cursor: text;
+}
+
+.terminal-text {
+  margin: 0;
+  font: inherit;
+  white-space: pre-wrap;
+  overflow-wrap: anywhere;
+  user-select: text;
+}
+
+.terminal-input {
+  display: flex;
+  align-items: baseline;
+}
+
+.terminal-prompt {
+  white-space: pre;
+}
+
+.terminal-input input {
+  flex: 1;
+  min-width: 0;
+  padding: 0;
+  border: none;
+  outline: none;
+  background: transparent;
+  color: rgb(222 222 222);
+  caret-color: rgb(222 222 222);
+  font: 16px ui-monospace, Menlo, Consolas, 'Courier New', monospace;
+}
+
+.terminal-keys {
+  display: flex;
+  gap: 6px;
+  flex: none;
+  overflow-x: auto;
+  padding: 6px;
+  background: rgb(32 32 32);
+}
+
+.terminal-chip {
+  flex: none;
+  min-width: 44px;
+  min-height: 44px;
+  padding: 0 12px;
+  border: 1px solid rgb(90 90 90);
+  border-radius: 8px;
+  background: rgb(48 48 48);
+  color: rgb(222 222 222);
+  font: 14px ui-monospace, Menlo, Consolas, monospace;
+  cursor: pointer;
+}