fix: resolve review #004 findings W1-W4 + close review gate

W1 (call/protocol/abort-cascade-wiring): wire AbortCascade into
CallAdapter handle_stream for EVENT_ABORTED. Cascades with
AbortPolicy::AbortDependents, aborts root, no descendant frames on
wire (ADR-016 Decision 2). Two integration tests added.

W2 (core/endpoint-client-fingerprint): extract TLS client cert
fingerprint in dispatch_quinn (SHA256:<hex> of leaf cert DER via
peer_identity) and dispatch_iroh (ed25519:<hex> of peer NodeId).
Fingerprint format documented in auth.md. Server config change
(with_no_client_auth → request-but-don't-require) deferred to new
follow-up task core/endpoint-request-client-cert.

W3 (vault/mnemonic-debug-redaction): replace Mnemonic derive(Debug)
with manual redacting impl (phrase: "[REDACTED]"). Seed confirmed
no Debug impl. Redaction test added.

W4 (core/auth-apikey-resources): Option B — drop entry.resources from
spec. External identities (token/fingerprint) grant scopes only;
resource-scoped ACLs are composition-internal (ADR-015/022). auth.md
corrected + limitation documented. Two tests confirm empty resources.

review-post-impl-fixes: all 4 verified, workspace green (326 tests,
0 failures, 0 clippy warnings). Review #004 status → resolved.

Graph: 34 tasks, 12 gens.

tasks/core/endpoint-client-fingerprint.md

@@ -1,7 +1,7 @@
 ---
 id: core/endpoint-client-fingerprint
 name: Extract TLS client certificate fingerprint in endpoint dispatch (ADR-004)
-status: pending
+status: completed
 depends_on: []
 scope: narrow
 risk: medium
@@ -115,4 +115,17 @@ in the codebase before committing.
 > client certs. The extraction code is correct either way — it returns
 > `None` when no cert was presented, which is the current behavior, so
 > landing extraction first is a safe no-op until the server config
-> changes.
+> changes.
+
+## Summary
+
+Added `extract_quinn_client_fingerprint` (leaf cert DER → `SHA256:<hex>`
+via `peer_identity()` downcast) and `extract_iroh_client_fingerprint`
+(peer `NodeId` → `ed25519:<hex>`). Both dispatch functions now pass the
+extracted fingerprint to `build_auth_context`. Fingerprint format
+documented in `auth.md` (table: quinn X.509 vs iroh raw Ed25519).
+Server config still uses `with_no_client_auth()` — extraction is a safe
+no-op. Follow-up task `core/endpoint-request-client-cert` created for the
+server config change. Two unit tests cover fingerprint format +
+determinism. `cargo test -p alknet-core --all-features` (59 tests) and
+clippy clean.