feat(adapters): from_jsonschema single-endpoint adapter + shared forwarding core

- src/adapters/forward.rs: shared HTTP forwarding core (extracted from
  old from_openapi) — HttpServiceConfig/HttpAuthScheme, build_request
  with capabilities-based credential injection (no env vars), forward
  + forward_stream (SSE projection), parse_sse_frames
- src/adapters/from_jsonschema.rs: FromJsonSchema OperationAdapter
  (ADR-066) — one registration per call, FromJsonSchema provenance
  (leaf, Internal default), Sub -> HandlerKind::Stream (text/event-stream)
- adapted to alkcall 0.1.1: OperationType::Sub, alkcall::client
  adapter traits

Verified: cargo test (106 lib tests), clippy -D warnings, fmt.

tasks/adapters/from-jsonschema.md

@@ -1,7 +1,7 @@
 ---
 id: adapter-from-jsonschema
 name: from_jsonschema single-endpoint adapter
-status: pending
+status: completed
 depends_on: [client-http-host]
 scope: narrow
 risk: low
@@ -23,9 +23,9 @@ from_openapi.
 
 ## Acceptance Criteria
 
-- [ ] Adapter ported; one registration per call, correct provenance
-- [ ] Forwarding round-trip test against a local mock server
-- [ ] `cargo test` passes
+- [x] Adapter ported; one registration per call, correct provenance
+- [x] Forwarding round-trip test against a local mock server
+- [x] `cargo test` passes
 
 ## References
 
@@ -39,4 +39,26 @@ from_openapi.
 
 ## Summary
 
-> Agent fills on completion.
+Ported `src/adapters/from_jsonschema.rs` per ADR-066, plus the shared
+forwarding core it depends on:
+
+- `src/adapters/forward.rs`: extracted from old from_openapi —
+  HttpServiceConfig/HttpAuthScheme, build_request (path templates,
+  query split, body key, credential injection from
+  OperationContext.capabilities), forward (2xx -> JSON/text/bytes
+  envelope; non-2xx -> declared code or HTTP_<status>), forward_stream
+  (SSE -> ResponseEnvelope stream, ADR-049), parse_sse_frames.
+  Pre-positions the from_openapi port to reuse the same core.
+- `src/adapters/from_jsonschema.rs`: FromJsonSchema OperationAdapter —
+  one HandlerRegistration per call (spec + path template + method),
+  FromJsonSchema provenance (leaf, composition_authority None,
+  scoped_env None, Internal default), Sub op type -> HandlerKind::Stream
+  expecting text/event-stream.
+
+Adaptations for alkcall 0.1.1: OperationType::Sub (not Subscription),
+adapter imports via alkcall::client::{AdapterError, OperationAdapter}.
+
+11 tests: registration shape, handler kinds (Query/Sub/Mutation),
+build_request bearer-from-capabilities + path/query split, forwarding
+round-trip vs local mock server (200/404/500), SSE subscription stream,
+no-env-vars invariant. 106 lib tests green.