fix(const): the AppType crawler lower-cases IANA service names, so TCP.cailic is not the registrar's CAIlic #2551

From the 2026-11-01 conventions audit, re-verified on 73add05a3. registry-protocol.rst, "RFC-Directed Case Sensitivity" and the audit row for TCP, UDP, SCTP and DCCP: a registry's spelling is never quietly normalised, and member names come from the service-name column "in the registrar's own spelling".

• AppType.records in pcapkit/vendor/reg/apptype/apptype.py builds svc = item[0].strip().lower() or ..., so every service name is lower-cased before it is generated into pcapkit/const/reg/apptype/{tcp,udp,sctp,dccp}.py.
• IANA's service-names-port-numbers.csv keeps the case: CAIlic,216, tnETOS,377, warmspotMgmt,1074. The members are cailic = 216, 'cailic', ..., tnetos and warmspotmgmt. The row's own example, tcpmux, is already lower case, which hides the gap.
• RFC 6335 §5.1 makes service names case-insensitive, but the page puts that in a lookup override, never in renamed members. No ruling on lower-casing member names turned up in design: should the non-registry helper enums share a lookup interface, or be made strictly immutable? #877, test(const): audit every registry case sensitivity against its source specification #903, design: AppType is str-valued with 1,004 port=-1 members, unlike its int-valued sibling registries #732 or const: bring the 16 bespoke registries onto EnumRegistry, after fixing the base's str-key dispatch #860.
• Probe: curl -s https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv | grep -E '^(CAIlic|tnETOS|warmspotMgmt),'.

Decision needed: is the page or the generator wrong?

1. Keep the registrar's spelling in svc and the member name, with an alias for each old lower-case name (a bare rename is observable).
2. Keep the lower-casing and record it on the page as an exception citing RFC 6335 §5.1.
   Recommendation: 2, because RFC 6335 §5.1 already treats the names as case-insensitive, and 1 renames every mixed-case member and needs an alias for each.
   Fix: per the decision, in the template, not the generated files. Option 2 also edits registry-protocol.rst, which feat(registry): foundation.registry wrappers for IPX and SCTP sub-maps; record the convention (#2511) #2521 edits.