docs(architecture): add alknet-call crate spec, ADR-012, resolve OQ-07

Add architecture specs for the alknet-call crate:

- call-protocol.md: CallAdapter, EventEnvelope wire format, bidirectional
  stream model with ID-based correlation, PendingRequestMap, protocol
  operations (call/subscribe/batch/schema), per-request identity resolution,
  connection/stream lifecycle, error codes

- operation-registry.md: OperationSpec, async Handler type, OperationRegistry,
  AccessControl with trusted call bypass, OperationEnv with context
  propagation (parent_request_id, identity inheritance), service discovery,
  irpc integration layering, naming convention (no leading slash in names)

- ADR-012: Call protocol uses bidirectional QUIC streams with EventEnvelope
  framing and ID-based correlation. Protocol is stream-agnostic and symmetric.
  Resolves OQ-07.

Key design decisions:
- Handler type is async (Fn returning Pin<Box<dyn Future>>)
- OperationEnv::invoke propagates parent context (identity, metadata,
  parent_request_id)
- Identity resolution is per-request, not per-connection
- Operation names without leading slash (fs/readFile, not /fs/readFile)
- Batch is a client-side pattern, not a protocol primitive (OQ-14)
- Phase 1 uses service/op paths, node prefix added later (OQ-13)

Also: promote ADR-010 and ADR-011 from Proposed to Accepted, add OQ-13
and OQ-14 to open-questions.md.

docs/architecture/decisions/011-authcontext-structure.md

@@ -2,7 +2,7 @@
 
 ## Status
 
-Proposed
+Accepted
 
 ## Context