fix: deep code review passes 25-28 - 18 issues fixed

[mikemiles-dev]

Pass 25 (6 fixes):

• IPFIX V9 options template validation aligned with V9 parser (reject individual zero-length fields)
• would_accept() false negative causing data truncation fixed
• set_pending_flows_config(None) now records dropped metrics
• IPFIX replay flowset count bound added (consistent with V9)
• YAF DnsSRVTarget (219) type corrected to String
• YAF SslPublicKeyLength (250) type corrected to UnsignedDataNumber

Pass 26 (3 fixes):

• IPFIX "withdraw all" templates implemented per RFC 7011 §8.1
• V9 replay flowset limit uses break instead of continue
• IPFIX withdrawal+redefinition in same flowset no longer drains pending flows

Pass 27 (3 fixes):

• Fuzz round-trip target uses fresh parser for re-parse (no accumulated state)
• README: 3 missing examples added
• Redundant test renamed to test_v5_serialization_single_packet

Pass 28 (3 fixes):

• IPFIX withdraw-all now drains only same-type pending flows (not cross-type)
• test_pcap_iterator_api now only counts successful parses
• README v0.7.0 breaking change note updated for v1.0.0

Additional improvements:

• Dead macro parameter removed from impl_try_from!
• TemplateHooks::clear() method added
• test_parser_builder_with_field_count_limits made non-vacuous
• test_parser_builder_comprehensive strengthened with functional verification