chore: consume alkcall 0.7.0; W1/CF-005 resolved — identity seam validated

alkcall 0.7.0 resolved every open downstream-consumer finding,
including this crate's reverse-flow POC W1 (filed as ledger CF-005,
with the CF-006 corollary):
- CF-005 (a): ServingConfig.identity — the explicit override
- CF-005 (b): transport Connection::identity() propagates to
  channel 0 — set_identity before dialing is the mTLS/QUIC path
- CF-006: the establisher/pump handler receive the per-call opener
  identity (dispatch-resolved), not the install-time context
- CF-007: ADR-016 code list completed (doc-only)
- F-1 (POC finding): the ChannelPlan type doc now carries the
  Send + Sync payload constraint

alktunnels updates:
- Cargo.toml: alkcall 0.6.0 -> 0.7.0 (lockfile resolves 0.7.0)
- AGENTS.md convention 11: pin note updated; the 0.7.0 identity
  surface marked load-bearing (precedence order + per-call opener)
- AGENTS.md architecture context: CF-005/CF-006 row added; the
  'What the POC does NOT settle' list replaced with the accurate
  settled state (Phase 0 complete; Phase 1 = the spec)
- reverse-poc-summary: W1 marked RESOLVED with the remediation
  validated from the POC's topology (16 tests over 0.7.0: transport
  identity alone authorizes, ServingConfig.identity overrides,
  identity-less fails closed, CF-006 witness); F-1 marked documented
  upstream; what-the-POC-does-not-validate and verification blocks
  updated
- phase-0-findings OQ-TN-10: reverse POC entry notes the 0.7.0
  re-validation and W1 resolution

The reverse POC (/workspace/alktunnels-reverse-poc, 8b35818) re-
validated: the default harness now authorizes on transport identity
alone — the 0.6.0-era auth_token workaround is dead code.

Verification: cargo test, clippy --all-targets -D warnings,
fmt --check, wasm32 check, doc --no-deps — all clean

docs/research/phase-0-findings.md

@@ -773,11 +773,15 @@ Phase 0 may need (in rough priority order, per the SDD process's
    closes: no advertisement op needed — the listener is the hub's own
    local resource; a far-side listener is a producer-side listen
    establisher over the same open op. Findings: F-1 (plan payloads
-   must be `Send + Sync`), F-2 (UDP raw pass-through cannot carry
-   empty datagrams — the length-framed codec is mandatory, second
-   validation of the codec decision). W1 (connect-side serving path
-   resolves identity only via payload `auth_token`) filed for the
-   alkcall ledger.
+   must be `Send + Sync` — documented upstream in 0.7.0), F-2 (UDP
+   raw pass-through cannot carry empty datagrams — the length-framed
+   codec is mandatory, second validation of the codec decision). W1
+   (connect-side serving path resolves identity only via payload
+   `auth_token`) filed for the alkcall ledger — **RESOLVED by alkcall
+   0.7.0 (CF-005/CF-006)**; the POC re-validated over 0.7.0 (16
+   tests): transport identity authorizes alone, `ServingConfig.
+   identity` overrides, identity-less fails closed, and the
+   establisher sees the per-call opener identity.
 3. **Unix socket + stdio bridge POC** — cheap; validates "substrate
    agnostic" beyond IP substrates.
 4. **Two-pump helper extraction spike** — OQ-TN-06, only after 1–3.
@@ -880,11 +884,12 @@ Candidate reading for the research specialist (to be expanded):
 - [x] Targeted POC(s) run + summary (OQ-TN-10) — UDP POC DONE
       (2026-09-06, `poc-summary.md`); reverse-flow POC DONE
       (2026-09-07, `reverse-poc-summary.md` — the `-R` shape validated
-      end-to-end over alkcall 0.6.0; findings F-1/F-2; W1 filed for
-      the upstream ledger). Remaining items (#3 unix/stdio, #4 helper
-      spike) are spec-scope: #3 folds into the real crate's tests
-      (pump agnosticism confirmed twice), #4 resolved by alkcall 0.6.0
-      (ADR-050)
+      end-to-end over alkcall 0.6.0, re-validated over 0.7.0 with the
+      CF-005/CF-006 identity remediation; findings F-1/F-2; W1 filed
+      upstream and RESOLVED). Remaining items (#3 unix/stdio, #4
+      helper spike) are spec-scope: #3 folds into the real crate's
+      tests (pump agnosticism confirmed twice), #4 resolved by
+      alkcall 0.6.0 (ADR-050)
 - [x] Two-pump helper convergence input gathered (OQ-TN-06) — the POC
       gives both shapes (producer `pump_halves`, consumer
       `take_halves` + copy): same shape modulo channel side; the