…at_hash_sorted, dbh defaults

TraceLevel / trace:
  * STORE accepts "SQL|foo|3" strings (routed through
    parse_trace_flags) and treats undef as a no-op, matching real
    DBI's "local $h->{TraceLevel} = undef" idiom.
  * $dbh->trace($level, $file) now routes the 3-arg form to
    DBI::trace so handle-level calls install the process-global
    trace filehandle the same way the class method does.
  * parse_trace_flags carps on unknown flags (when Warn is true).
  * Statement handles inherit TraceLevel from the parent dbh in
    _new_sth.

DBI->internal:
  * Now built through _new_drh so it's a proper tied outer handle
    with FETCH / STORE hitting DBD::_::common. DBD::Switch::dr
    inherits from DBI::dr so isa('DBI::dr') is true. Attribution
    and Active defaults are populated so $switch->{Attribution}
    returns "DBI $VERSION by Tim Bunce".

dbh default attributes:
  * _new_dbh now installs Warn, PrintError / PrintWarn (the
    latter off by default unless `-w`), RaiseError, RaiseWarn,
    AutoCommit, CompatMode, ShowErrorStatement, ChopBlanks,
    LongTruncOk, Executed, ErrCount, FetchHashKeyName, and
    LongReadLen with their real-DBI defaults.
  * DBI.pm's connect wrapper no longer skips re-applying
    user-supplied attrs when a key is already present on the
    dbh; the user's connect attr hash is authoritative.

_concat_hash_sorted:
  * Rewritten to match real DBI's XS behaviour: undef input ->
    undef, non-HASH -> croak, keys unquoted, auto-guess
    numeric-vs-lexical sort when sort_type is undef, $a <=> $b
    or $a cmp $b for numeric sort.

Unknown-attribute warnings:
  * DBD::_::common FETCH / STORE now carp on uppercase-prefixed
    attributes that aren't in a known allow-list (mirroring
    DBI::PurePerl's %is_valid_attribute). Lowercase keys,
    private_*, dbd_*, dbi_* prefixes are always accepted.

Per-test deltas (direct ./jperl):
  * t/01basics.t:     95/130 -> 100/100 (halts on unrelated DBI::hash)
  * t/05concathash.t: 11/41  -> 41/41
  * t/06attrs.t:      136/166 -> 142/166
  * t/09trace.t:      83/99  -> 99/99
  * t/17handle_error.t: 84/84 maintained

Generated with [Devin](https://cli.devin.ai/docs)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>