feat(call): OperationAdapter trait + AdapterError + from_jsonschema (ADR-017 §5)
- client module: defines the async OperationAdapter trait
(import() -> Result<Vec<HandlerRegistration>, AdapterError>) and the
#[non_exhaustive] AdapterError enum (string-message payloads: DiscoveryFailed,
SchemaParse, Transport, Unauthorized, Conflict). The trait lives in alknet-call
where the types live; implementations live with their transport deps.
- from_jsonschema: schema-only registration producing a FromJsonSchema-provenance
HandlerRegistration with no real handler (placeholder errors if invoked),
None authority/scoped_env, empty capabilities, remote_safe false (ADR-028 §4).
Implements OperationAdapter; malformed (non-object) schema returns
AdapterError::SchemaParse. No network I/O.
- Re-exported from lib.rs.
- Tests: trait compiles for Ok and Err adapters; from_jsonschema bundle shape;
placeholder handler errors; OperationAdapter import Ok + SchemaParse paths.
All 178+N tests pass, clippy + fmt clean.
Unblocks alknet-http Phase 1 (from_openapi/from_mcp adapter implementations).
Refs: tasks/call/client/operation-adapter-trait.md, tasks/call/client/from-jsonschema.md
Refs: docs/architecture/decisions/017-call-protocol-client-and-adapter-contract.md §5
Refs: docs/architecture/crates/call/client-and-adapters.md