style(matrix): separate _MATRIX_PERMANENT_ERRCODES from the preceding function

The stack inserted the errcode table directly after _strip_reply_fallback's
return with no blank lines, which reads as if the constant belongs to the
function body and trips E305. Two blank lines restore the module-level
boundary; no behaviour change.

plugins/platforms/matrix/adapter.py

@@ -195,6 +195,8 @@ def _strip_reply_fallback(body: str) -> str:
                 continue
         stripped.append(line)
     return "\n".join(stripped) if stripped else body
+
+
 # Auth errcodes that genuinely require re-authentication (never retried).
 _MATRIX_PERMANENT_ERRCODES = frozenset({
     "m_unknown_token",