docs(arch): sync specs to transport generalization sweep (ADR-064, ADR-065)

Three code commits landed a clean sweep discovered when building an
external app against the crates. This syncs the architecture specs to
match the codebase and amends the affected decisions.

ADR-064 (supersedes ADR-005): irpc was never integrated — no .rs file in
the workspace ever imported it. The wire protocol (wire.rs) is hand-rolled
length-prefixed JSON; the EventEnvelope shape was derived from the
@alkdev/pubsub TypeScript prior art (ADR-013), not from irpc. ADR-005's
premise ('irpc as the call protocol foundation') was never implemented as
stated. Superseded with a clear header; the body is kept as historical
record.

ADR-065: Connection::from_stream / from_bidi — Connection now accepts any
AsyncRead + AsyncWrite pair via ConnectionKind::Stream (yield-once
accept_bi contract: QUIC yields many streams, everything else yields one
then ConnectionClosed). Unblocks TCP+TLS, SSH channel dispatch,
WebTransport streams, and wasm streams through the same HandlerRegistry
as QUIC connections, with zero handler code changes. MockConnection /
ConnectionKind::Mock removed (tests use from_stream with sink/empty).
Stream-level Mock variants renamed to Stream (they were already generic).

Amended ADRs: ADR-003 (irpc removed from dep table), ADR-007 (from_stream
opens the server-side door; MockConnection removed), ADR-010 (TCP+TLS can
now dispatch through the registry via from_bidi; iroh 1.0 migration noted).

Updated specs: core-types.md (Connection/SendStream/RecvStream sections),
endpoint.md (TCP section, iroh note), call-protocol.md, operation-registry
(irpc Integration section replaced), overview.md, http-server.md,
webtransport.md, call README. OQ-09 (WASM) resolution amended: the
Connection door is now open via from_stream; the accept-loop runtime door
remains closed (tokio doesn't run on WASM).

See docs/research/transport-generalization/findings.md for the full trace.

docs/architecture/decisions/008-secret-service-integration.md

@@ -64,7 +64,7 @@ This is analogous to the reverse-proxy admin key pattern (ADR-028 in the reverse
 ## References
 
 - ADR-003: Crate decomposition (alknet-vault is standalone)
-- ADR-005: irpc as call protocol foundation (for alknet-call; the vault no longer uses irpc — see ADR-025)
+- ADR-005: irpc as call protocol foundation (superseded by ADR-064 — irpc was never integrated; the vault no longer uses irpc — see ADR-025)
 - ADR-009: One-way door decision framework
 - ADR-014: Secret material flow and capability injection (specifies the mechanism this ADR described in prose)
 - ADR-025: Vault local-only dispatch (dropped irpc from the vault; direct method calls only)