Drop the interaction-requirements manifest entry

The manifest's ID vocabulary is aligned entry-by-entry with the
TypeScript SDK's requirements suite, so a new ID is a maintainer
decision rather than something to mint alongside a bug fix. The
client tests stand on their own without it.

No-Verification-Needed: manifest-only revert with no runtime surface

Author: maxisbey

tests/interaction/_requirements.py

@@ -3278,19 +3278,6 @@ def __post_init__(self) -> None:
             "at the transport seam."
         ),
     ),
-    "hosting:client:legacy-inbound-modern-vocabulary-dropped": Requirement(
-        source=f"{SPEC_2026_BASE_URL}/basic/versioning",
-        behavior=(
-            "A client on a pre-2026 session that receives 2026-07-28 result vocabulary "
-            "(resultType, ttlMs, cacheScope) drops those fields before parsing, so a value "
-            "the 2026-07-28 types reject cannot fail the call and the result shows its defaults."
-        ),
-        deferred=(
-            "Client-inbound seam, covered by tests/client/test_session.py::"
-            "test_cache_hints_from_a_legacy_server_never_reach_the_result and "
-            "test_a_2026_result_type_tag_from_a_legacy_server_never_reaches_the_result"
-        ),
-    ),
     "hosting:http:modern:tools-call-stateless": Requirement(
         source=f"{SPEC_2026_BASE_URL}/basic/transports/streamable-http",
         behavior=(