feat: rename ALPN prefix from alknet/ to alk/ (v0.1.1)

- CHANNELS_ALPN: b"alknet/channels" → b"alk/channels"
- CallAdapter::alpn(): b"alknet/call" → b"alk/call"
- derive_alpn_from_op_name: alknet/ prefix → alk/ prefix
- All ALPN string literals in src/ and docs/ updated
- ADR-004 amended with prefix rename rationale
- AGENTS.md, README.md updated
- Version bumped to 0.1.1

Review: docs/reviews/003-alpn-prefix-rename.md

Verification:
- cargo test: 542 passed, 0 failed
- cargo clippy --all-targets -- -D warnings: clean
- cargo fmt --check: clean
- cargo doc --no-deps: clean

docs/architecture/decisions/045-alknetclient-native-dial-seam.md

@@ -222,7 +222,7 @@ in the type.
 > `ConnectionCredentials`, not `CallCredentials`. `CallCredentials`
 > couples the dial to the call protocol (its `auth_token` field is a
 > call-protocol / hub-layer concept — bearer-token identity correlation
-> for browsers and `alknet/register`, not a transport credential). The
+> for browsers and `alk/register`, not a transport credential). The
 > dial uses only the transport-identity dimensions (`local_identity` +
 > `remote_identity`); those move to `ConnectionCredentials` in
 > `alknet-core`. All three dial signatures unify on
@@ -350,9 +350,9 @@ removed rather than left as a vestigial enum. If `spawn_dispatch` ever
 gains a failure path, a fresh error type is cleaner than retrofitting
 this one.
 
-### 6. `alknet/register` is a dialable ALPN (entry point, wire protocol deferred)
+### 6. `alk/register` is a dialable ALPN (entry point, wire protocol deferred)
 
-`AlknetClient::dial_quic` / `dial_tcp_tls` can dial the `alknet/register`
+`AlknetClient::dial_quic` / `dial_tcp_tls` can dial the `alk/register`
 ALPN — the native registration entry point, parallel to HTTP
 registration (OQ-58) but without the HTTP layer. The connection is an
 **entry point** (ADR-086 §2): accepted without an established peer
@@ -364,7 +364,7 @@ Two registration cases, both hub concerns and both optional:
 
 - **Token registration** — a freshly-provisioned worker (docker,
   vast.ai, runpod) generates its local identity, dials the hub on
-  `alknet/register`, presents the one-time registration token, and
+  `alk/register`, presents the one-time registration token, and
   enrolls its key. The hub creates a `PeerEntry` and returns a session
   credential.
 - **No-token (open) registration** — a hub that hosts public services
@@ -372,13 +372,13 @@ Two registration cases, both hub concerns and both optional:
   token. The enrollment creates a `PeerEntry` with no token
   requirement.
 
-The `alknet/register` **wire protocol** (the handshake on the
+The `alk/register` **wire protocol** (the handshake on the
 `Connection` after the dial — what frames the client sends, what the
 hub returns) ties into the call crate's ACL and the OQ-58 enrollment
 model. It is **deferred** to a dedicated ADR — this ADR names the ALPN
 and its entry-point role; it does not specify the wire protocol. The
 HTTP registration endpoint (OQ-58) remains the first implementation;
-`alknet/register` is the native analogue that removes the HTTP
+`alk/register` is the native analogue that removes the HTTP
 dependency for workers that have no HTTP client.
 
 ### 7. OQ-55 is resolved for the native dial
@@ -467,7 +467,7 @@ several possible native clients sharing the same wire protocols.
   on connection failure. `AlknetClient` provides both dials; the
   fallback policy is a caller concern (or a future `dial_with_fallback`
   helper — two-way-door).
-- **`alknet/register` is named.** The native registration entry point
+- **`alk/register` is named.** The native registration entry point
   has a home in the ALPN registry, parallel to HTTP registration. The
   wire protocol is deferred, but the ALPN and its entry-point role are
   decided — a worker that has no HTTP client can register natively.
@@ -496,7 +496,7 @@ several possible native clients sharing the same wire protocols.
   consistency is in the rule, not in the type. This is the same
   exception as the server side (ADR-082, ADR-087 §3) — unavoidable,
   and isolated to one dial method.
-- **The `alknet/register` wire protocol is still deferred.** This ADR
+- **The `alk/register` wire protocol is still deferred.** This ADR
   names the ALPN and its role; the handshake protocol (token/no-token,
   the frames, the `PeerEntry` creation, the session credential return)
   is a separate ADR tied to OQ-58. A worker cannot register natively
@@ -520,7 +520,7 @@ boilerplate. The three-dial API (`dial_quic` / `dial_tcp_tls` /
 `dial_iroh`) is one-way — changing the signatures after consumers exist
 is a rewrite. The internal implementation (how `ConnectionCredentials`
 feeds `TlsClientConfig::new`, how the iroh dial maps the
-`Ed25519SecretKey`) is two-way. The `alknet/register` ALPN name is
+`Ed25519SecretKey`) is two-way. The `alk/register` ALPN name is
 one-way (wire compatibility); its wire protocol is two-way until the
 dedicated ADR lands.
 
@@ -551,7 +551,7 @@ dedicated ADR lands.
   (the take-over `AlknetClient` feeds)
 - [ADR-022](022-call-protocol-client-and-adapter-contract.md) —
   `CallClient::spawn_dispatch` (the take-over `AlknetClient` feeds)
-- OQ-58 — worker registration flow (the HTTP path; `alknet/register`
+- OQ-58 — worker registration flow (the HTTP path; `alk/register`
   is the native analogue)
 - `docs/architecture/crates/channels/channel-client.md` §"Relationship
   to `AlknetClient`" — the deferral this ADR resolves