fix: Set terminal env vars to prevent os.get_terminal_size() errors

meshcli calls os.get_terminal_size() which fails without a TTY.
Setting COLUMNS, LINES, and TERM=dumb provides fallback values.

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

meshcore-bridge/bridge.py

@@ -90,13 +90,20 @@ class MeshCLISession:
         logger.info(f"Starting meshcli session on {self.serial_port}")
 
         try:
+            # Set terminal size env vars for meshcli (prevents os.get_terminal_size() errors)
+            env = os.environ.copy()
+            env['COLUMNS'] = '120'
+            env['LINES'] = '40'
+            env['TERM'] = 'dumb'
+
             self.process = subprocess.Popen(
                 ['meshcli', '-s', self.serial_port],
                 stdin=subprocess.PIPE,
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE,
                 text=True,
-                bufsize=1  # Line-buffered
+                bufsize=1,  # Line-buffered
+                env=env
             )
 
             logger.info(f"meshcli process started (PID: {self.process.pid})")