fix(schema): SMF_DPD option at the end of the header raises TypeError from smf_i_dpd_id_len #1195

Describe the bug
When an SMF_DPD option sits in the last two bytes of a HOPOPT or IPv6-Opts header, parsing it raises a bare TypeError instead of an in-library error. The ConditionalField skips len, so pkt['len'] is the NO_VALUE sentinel, and smf_i_dpd_id_len subtracts from it without a guard. This happens at pcapkit/protocols/schema/internet/hopopt.py:159, and schema/internet/ipv6_opts.py:159 has the same line.

To Reproduce
On origin/main (a2f989fbd), run HOPOPT(io.BytesIO(bytes.fromhex('3b00010200000800'))). It raises TypeError: unsupported operand type(s) for -: 'NoValueType' and 'int'. IPv6_Opts behaves the same way.

Expected behavior
A truncated option raises an in-library error, as its siblings already do. CALIPSO (…0700) raises FieldValueError: invalid CALIPSO option length: 0, and MPL (…6d00) raises the equivalent MPL error.

The #1193 worker found this, and the #1194 cross-review reproduced it. That review swept all 256 option types at that position, and only type 8 raises TypeError. I re-ran it on main.