chore: consume alkcall 0.6.0; OQ-TN-06 resolved by ADR-050

alkcall 0.6.0 landed the review 007 remediation (filed from this
crate's UDP POC pass):
- R-01: Establishment carries the plan (ADR-049 amendment 2) —
  typed-opaque ChannelPlan, OpenHandler gains the plan param, the
  wrapper threads it; the POC's side-channel HandleHandoff and its
  same-resource race are dead (the establisher returns the dialed
  handle: Ok(Establishment::new(plan)))
- R-02: OpenHandler JoinHandle lifetime contract documented (early
  return = teardown-at-birth) + yield-once acceptance flag and
  debug! birth-teardown hint
- R-03: pump_bidi pinned upstream (ADR-050) — two pumps,
  shutdown-on-completion, (u64, u64) copy counts, errors EOF-shaped

alktunnels updates:
- Cargo.toml: alkcall 0.5.0 -> 0.6.0 (lockfile resolves 0.6.0)
- AGENTS.md convention 8: use alkcall channels::pump_bidi, do not
  hand-roll; await it inline inside the OpenHandler's task
- AGENTS.md convention 11: pin note updated; amendment 2 marked
  load-bearing (Establishment::new replaces side-channel handoff)
- AGENTS.md convention 13: fixed ADR citation bug (was "alkcall
  ADR-024, ADR-050" — those are peer-graph-routing and pump-bidi;
  intended targets are alknet ADR-024/ADR-050 with their alkcall
  ports ADR-019/ADR-011)
- AGENTS.md architecture context: ADR-050 + ADR-049 amendment 2 rows
- phase-0-findings OQ-TN-06: RESOLVED — pump_bidi landed upstream;
  the POC is cited as convergence input alongside alktty and the
  assembly-layer copies; Phase 1 consumes the helper
- phase-0-findings OQ-TN-09: implementation note updated —
  Establishment::new(plan) replaces the handoff sketch
- poc-summary: resolutions addendum for both upstream findings
  (R-01/R-02/R-03 with the typed-opaque and (u64, u64) deviations
  recorded); references note 0.6.0 supersession

Verification: cargo test (0 tests, ok), clippy --all-targets
-D warnings, fmt --check, wasm32 check, doc --no-deps — all clean

AGENTS.md

@@ -65,8 +65,8 @@ just spawned implementation agents.
    expected on public API. Inline `//` comments only when the user asks
    or when a non-obvious safety/correctness constraint would otherwise be
    missed (e.g., "a two-pump tunnel must shut down the opposite sink on
-   pump completion — `try_join!` alone deadlocks; see alkcall's
-   channels-adapter spec / alknet ADR-078").
+   pump completion — `try_join!` alone deadlocks; see alkcall ADR-050's
+   `pump_bidi` / alknet ADR-078").
 
 2. **Error handling** — `thiserror` for library error types
    (`TunnelError`; `HandlerError`/`StreamError` come from
@@ -131,10 +131,14 @@ just spawned implementation agents.
    canonical two-pump handler (one pump per direction). Each pump MUST
    shut down the opposite sink when it completes; `tokio::try_join!`
    alone deadlocks. This was POC-validated in the alknet-channels POC
-   (Target 3) and pinned as alknet ADR-078. The channels layer drops
-   all per-channel senders on transport EOF — rely on that for
-   teardown, and emit EOF sentinels (zero-length chunks) on clean
-   sink shutdown.
+   (Target 3), pinned as alknet ADR-078, and the helper is pinned
+   upstream as alkcall `channels::pump_bidi` (ADR-050, review 007
+   R-03) — use it; do not hand-roll the two-pump shape. The channels
+   layer drops all per-channel senders on transport EOF — rely on
+   that for teardown, and emit EOF sentinels (zero-length chunks) on
+   clean sink shutdown. Await `pump_bidi` inline inside the
+   `OpenHandler`'s task — the returned `JoinHandle` must track the
+   data-plane lifetime (R-02; early return = teardown-at-birth).
 
 9. **No forced local binding** — a tunnel must not require the producer
    (or consumer) to bind a local port. The POC's TCP-tunnel shape
@@ -163,12 +167,14 @@ just spawned implementation agents.
     `alkcall::core`. Do not vendor copies into this crate. alkcall is
     v0.5.x — breaking changes are expected at this major-zero stage;
     this is an early consumer, so we find and fix issues upstream
-    rather than working around them. Pin `alkcall = "0.5.0"` and bump
-    deliberately. The 0.5.0 establishment phase (ADR-049) is
-    load-bearing for this crate: tunnel opens use
+    rather than working around them. Pin `alkcall = "0.6.0"` and bump
+    deliberately. The 0.6.0 establishment surface (ADR-049 + amendment
+    2) is load-bearing for this crate: tunnel opens use
     `register_openable_with_establisher` so a refused target dial is
-    a typed `channel:open_failed` call error, never a phantom
-    channel.
+    a typed `channel:open_failed` call error, never a phantom channel,
+    and the establisher returns the dialed handle via
+    `Establishment::new(plan)` (typed-opaque `ChannelPlan`) — no
+    side-channel handoff.
 
 12. **BAST document for the wire format** — when the tunnel wire format
     gains binary framing (if any beyond pass-through), it carries a
@@ -190,7 +196,8 @@ just spawned implementation agents.
     (`provider.owns(id_ref, kind, &id, "tunnel")` — the 4-arg shape;
     `OwnershipStore::record` is the 3-arg shape). Tunnels reach local
     networks — treat the open gate as the security boundary. See
-    alkcall ADR-024, ADR-050.
+    alknet ADR-024 (registry layering, alkcall ADR-019), alknet
+    ADR-050 (ownership, alkcall ADR-011).
 
 14. **Feature flags** — substrate backends may be feature-gated if the
     need arises. The base crate should compile lean (no socket/platform
@@ -260,9 +267,13 @@ non-backend module changes.
   - alknet ADR-093 / alkcall ADR-035 — channels pure channel
     multiplexing (8-byte header, no `stream_type`); the tunnel payload
     is raw bytes inside the `BiStream`
-  - alknet ADR-078 — two-pump shutdown-on-completion (the tunnel
-    handler pattern; a helper extraction was deferred until a second
-    two-pump consumer exists — this crate is that second consumer)
+  - alknet ADR-078 / alkcall ADR-050 — two-pump shutdown-on-completion
+    (the tunnel handler pattern); the helper is pinned upstream as
+    `alkcall::channels::pump_bidi` — use it, do not hand-roll
+  - alkcall ADR-049 (amendment 2) — the establishment phase; the
+    establisher returns the dialed handle via `Establishment::new`
+    (typed-opaque `ChannelPlan`), replacing the POC's side-channel
+    handoff
   - alknet ADR-074 / alkcall ADR-038 — `ChannelConnection` as a
     `BidiStreamSource`; every handler (TTY, tunnel, call) receives a
     `Connection`