plan: PR-H1 — FEIGN_CLIENT role → CLIENT + HTTP_CLIENT capability (#32)

Implements propose merged in #28. Sequences after PR-F1 (#31, merged) and
PR-G1 (#30, merged). Hard rename — no deprecation alias, MCP bundle has
no users yet and breaking changes are explicitly allowed.

Single PR, ~115 LOC, ontology bump 8→9. Single source-of-truth flips at
ast_java.py:91 (role) and ast_java.py:114 (HTTP_CLIENT capability);
VALID_ROLES / VALID_CAPABILITIES are auto-derived so no java_ontology.py
edit needed.

9 new tests in tests/test_client_role_rename.py target ~290 passed,
4 skipped (281 baseline + 9).

Plan delta from propose: test #4 asserts warn-and-drop behaviour
(stderr warning + override silently dropped) matching actual
graph_enrich.py:443-447, 481-486, NOT raised ValueError as the propose's
example suggested.

Out of scope: async role/capability changes (MESSAGE_PRODUCER already
covers Kafka/Rabbit/JMS), auto-promoting RestTemplate/WebClient to
HTTP_CLIENT (brownfield-only opt-in), backwards-compat alias,
RegisterRestClient (followup #3).

Author: HumanBean17