4.23 sdds::Error and derived exceptions

• name:
  sdds::Error, sdds::IoError, sdds::FormatError, sdds::TypeError, sdds::StateError, sdds::LimitError
• description:
  Report SDDS++ failures using typed exceptions. The base class carries a stable ErrorKind and optional path, page, field, byte-offset, and row context in addition to the message returned by what().
• synopsis:
  sdds::ErrorKind kind() const noexcept;  
  const std::filesystem::path &path() const noexcept;  
  std::int64_t page() const noexcept;  
  const std::optional<std::string> &field() const noexcept;  
  const std::optional<std::uint64_t> &offset() const noexcept;  
  const std::optional<std::int64_t> &row() const noexcept;

• arguments:
  No arguments are required to inspect a caught exception.
• return value:
  The error category and diagnostic context. Page zero or an empty optional means that context was unavailable.
• exceptions:
  The accessors do not throw. Catch a specific derived type when recovery depends on the category, or catch const sdds::Error& at an application boundary.
• see also:
  Section 4.11 for recovery and resource-limit policies.