fix: terminal command execution via HTTP POST workaround

The WebSocket send mechanism fails with close code 1006 when client
tries to send data to server. Server never receives the message,
indicating a network/proxy layer issue that couldn't be fixed through
code changes or nginx configuration.

Solution: Bypass WebSocket send entirely by using HTTP POST to send
commands directly to the PTY.

Changes:
- Added sendTerminalInput() method to terminal-service.js that writes
  directly to PTY, bypassing WebSocket
- Added POST endpoint /claude/api/terminals/:id/input to server.js
- Modified launchCommand() in terminal.js to use fetch() with HTTP
  POST instead of WebSocket.send()

The WebSocket receive direction still works (server→client for output
display), only send direction (client→server for commands) is bypassed.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

server.js

@@ -1506,6 +1506,29 @@ app.delete('/claude/api/terminals/:id', requireAuth, (req, res) => {
   }
 });
 
+// Send input to terminal via HTTP (WebSocket workaround)
+app.post('/claude/api/terminals/:id/input', requireAuth, (req, res) => {
+  try {
+    const { data } = req.body;
+
+    if (!data) {
+      res.status(400).json({ error: 'Missing data parameter' });
+      return;
+    }
+
+    const result = terminalService.sendTerminalInput(req.params.id, data);
+
+    if (result.success) {
+      res.json({ success: true });
+    } else {
+      res.status(404).json({ error: result.error });
+    }
+  } catch (error) {
+    console.error('Error sending terminal input:', error);
+    res.status(500).json({ error: 'Failed to send input' });
+  }
+});
+
 // Get recent directories for terminal picker
 app.get('/claude/api/files/recent-dirs', requireAuth, (req, res) => {
   try {