feat: alkcall 0.9.0 adoption — bump to 0.7.0

The stub-sweep release changes no type alktty touches: the four
implemented stubs, the register_openable Pub-typed refusal (alktty's
op is Sub-typed), the register_imported Result return, and the removed
RelayError::PubTypedOpen are all surfaces alktty never exercises.

- alkcall requirement 0.8.1 -> 0.9.0; lockfile follows
- alktty 0.6.0 -> 0.7.0 (minor: raising the minimum alkcall requirement
  is ecosystem-coordination breaking on a 0.x crate)
- one test fix: `establisher_ok_on_valid_params` formatted a
  Result<Establishment, _> with {:?} — Establishment no longer derives
  Debug in alkcall 0.9.0; the assert now branches on Err and formats
  only the error

Verification: 113 default / 156 all-features tests, clippy
--all-targets -D warnings, fmt --check, cargo doc, fuzz corpus replay
(9 tests / 340 seeds), wasm32-unknown-unknown check + clippy,
publish --dry-run — all pass.

AGENTS.md

@@ -320,9 +320,12 @@ release and after touching `src/wire.rs`, `src/negotiation.rs`,
   `BiStream`, `BidiStreamSource`, `AuthContext`, `Identity`,
   `IdentityProvider`, `AccessControl`, `OwnershipProvider`,
   `OwnershipStore`, `InMemoryOwnershipStore`, `HandlerError`,
-   `StreamError`) come from `alkcall::core`. alkcall is v0.8.x —
-   breaking changes are expected at this major-zero stage; this is the
-   first real consumer, so we find and fix issues upstream rather than
-   working around them. Pin `alkcall = "0.8.1"` (0.8.1 fixes the
-   duplicate adopt/open channel-state destruction found by alkcall's
-   fuzz campaign) and bump deliberately.
+    `StreamError`) come from `alkcall::core`. alkcall is v0.9.x —
+    breaking changes are expected at this major-zero stage; this is the
+    first real consumer, so we find and fix issues upstream rather than
+    working around them. Pin `alkcall = "0.9.0"` (0.9.0 is the stub-sweep
+    release: the marked-pub open contract, `channel/control`,
+    `channel/resources/subscribe`, and `op/register` forward-through are
+    real implementations; `register_openable*` now refuses `Pub`-typed
+    specs — alktty's op is `Sub`-typed and unaffected) and bump
+    deliberately.