Clarify breakOnSystemExit default behavior in schema description

Describe the default as an ignore-list ({0, None}, plus 3 under Django/Flask) that breaks on any other code when uncaught-exception breaking is enabled, rather than the looser 'break on all non-zero exit codes'.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 24c2d34b-15f0-45d2-bd59-8ee042269d20

Author: rchiodo

package.json

@@ -187,7 +187,7 @@
                                 "type": "object"
                             },
                             "breakOnSystemExit": {
-                                "description": "Controls which SystemExit exit codes cause the debugger to break. Accepts an array of exit codes and/or inclusive ranges. Set to an empty array to never break on SystemExit. When omitted, the debugger uses its default behavior (break on all non-zero exit codes, ignoring successful exits).",
+                                "description": "Controls which SystemExit exit codes cause the debugger to break. Accepts an array of exit codes and/or inclusive ranges. Set to an empty array to never break on SystemExit. When omitted, the debugger's default applies: successful exits (SystemExit(0) and SystemExit(None), plus 3 under Django/Flask) are ignored, and any other code causes a break when uncaught-exception breaking is enabled.",
                                 "type": "array",
                                 "items": {
                                     "oneOf": [
@@ -437,7 +437,7 @@
                                 "type": "object"
                             },
                             "breakOnSystemExit": {
-                                "description": "Controls which SystemExit exit codes cause the debugger to break. Accepts an array of exit codes and/or inclusive ranges. Set to an empty array to never break on SystemExit. When omitted, the debugger uses its default behavior (break on all non-zero exit codes, ignoring successful exits).",
+                                "description": "Controls which SystemExit exit codes cause the debugger to break. Accepts an array of exit codes and/or inclusive ranges. Set to an empty array to never break on SystemExit. When omitted, the debugger's default applies: successful exits (SystemExit(0) and SystemExit(None), plus 3 under Django/Flask) are ignored, and any other code causes a break when uncaught-exception breaking is enabled.",
                                 "type": "array",
                                 "items": {
                                     "oneOf": [