feat: extract alknet-call into alkcall, vendor core types

Phase 1 of the alknet-call + alknet-channels unification. The call crate
is extracted verbatim from /workspace/@alkdev/alknet/crates/alknet-call
and the needed alknet-core types are vendored into src/core/ — alkcall is
the home for these types going forward (no separate alkcore crate).

Vendored core types (src/core/):
- auth.rs: Identity, AuthToken, AuthContext, IdentityProvider
- ownership.rs: OwnershipProvider, OwnershipStore, InMemoryOwnershipStore,
  OwnershipError
- types.rs: ProtocolHandler, Connection, BiStream, BidiStreamSource,
  SendStream, RecvStream, HandlerError, StreamError, Capabilities, Secret,
  IdentityAlreadySet
- Stripped: quinn/iroh/rustls deps, Connection::from_quinn/from_iroh
  (the dial lives in the consumer per ADR-089), config/credentials/
  fingerprint/store modules, ConfigIdentityProvider/IdentityStore

Call crate (src/client, src/protocol, src/registry/):
- Copied verbatim from alknet-call; alknet_core::{auth,types,ownership}
  rebound to crate::core::{auth,types,ownership}
- ALPN strings unchanged (alknet/call — wire-stable per ADR-006)
- No behavioral changes

Verification:
- cargo test: 343 passed (0 failed)
- cargo clippy --all-targets -- -D warnings: clean
- cargo fmt --check: clean
- cargo doc --no-deps: 1 pre-existing broken intra-doc link
  (CallAdapter in dispatch.rs — Phase 2 cleanup)

Next: Phase 2 — channels greenfield implementation + ALPN rename +
architecture doc porting.

Cargo.toml

@@ -0,0 +1,31 @@
+[package]
+name = "alkcall"
+version = "0.1.0"
+edition = "2021"
+rust-version = "1.85"
+license = "MIT OR Apache-2.0"
+description = "Call + channels RPC: structured JSON operations, streaming subscriptions, service discovery, and N-channel multiplexing over one transport stream"
+repository = "https://git.alk.dev/alkdev/alkcall"
+readme = "README.md"
+keywords = ["rpc", "json-rpc", "multiplexing", "wire-format", "alpn"]
+categories = ["network-programming", "asynchronous", "encoding"]
+exclude = [".opencode/", "docs/reviews/", "docs/research/", "docs/sdd_process.md", "Cargo.lock"]
+
+[lib]
+name = "alkcall"
+
+[features]
+default = []
+
+[dependencies]
+alktype = "0.1.0"
+tokio = { version = "1", features = ["full"] }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+async-trait = "0.1"
+tracing = "0.1"
+thiserror = "2"
+uuid = { version = "1", features = ["v4"] }
+futures = "0.3"
+parking_lot = "0.12"
+zeroize = { version = "1", features = ["alloc", "derive"] }