docs(adrs): reconcile WS-03 browser data-channel promise (ADR-067/048)

Record the v1 cut for browser-opened data channels over WS (review-001
WS-03): the design (ADR-067) stands; only the wiring is deferred.

- open-questions.md: add OQ-05 (deferred(scope: v1 cut)) with gap
  detail and deferred scope
- ADR-067: dated status amendment + v1-cut note at the data-channel
  step; References point to OQ-05
- ADR-048: dated reconciliation note — overlay bidirectionality is
  decided design, not a v1 implementation commitment
- websocket.md: status notes on §"Data channels for browsers" and
  upgrade step 7
- task review-001-ws-data-channel-decision: completed, Summary filled

Verification: taskgraph validate (38 tasks OK); cargo doc --no-deps
(pre-existing warnings only).

docs/architecture/open-questions.md

@@ -75,6 +75,35 @@ with their resolutions; new alkhttp OQs start at OQ-01.
   alkcall BAST document (`chunk-header.bast.json`); the client library
   lives outside this crate. Deferred(scope: browser UI work).
 
+### OQ-05: Browser-opened data channels over WS — v1 cut
+
+- **Origin**: review-001 finding WS-03 (`docs/reviews/001-initial-implementation-review.md`),
+  [ADR-067](decisions/067-websocket-carries-channels.md),
+  [ADR-048](decisions/048-websocket-native-session-not-gateway.md)
+- **Status**: deferred(scope: v1 cut — no browser consumer yet; reopened
+  when one lands)
+- **Priority**: medium
+- **Question**: ADR-067 §"Data channels for browsers" promises
+  browser-opened data channels (open ops on channel 0 → chunk
+  demultiplexing of channels 1..N), and ADR-048's bidirectionality
+  promise leans on the same connection-local machinery. The v1
+  implementation wires channel 0 only (`install_channel_zero` +
+  `Dispatcher::run_loop_single_stream`, `src/websocket/upgrade.rs`);
+  no `ChannelCore`/`register_openable`/`ChannelOperations` path exists
+  for a browser to open a data channel (grep-verified, review-001).
+  The design is decided (ADR-067: the browser opens data channels
+  exactly as any channels consumer — nothing new to design); what is
+  deferred is the *wiring*: passing the deployment's openable-ALPN
+  registrations and `ChannelLifecyclePolicy` through the WS upgrade
+  path, plus a browser-opened-channel end-to-end test.
+- **Resolution**: (pending — v1 cut recorded 2026-08-29 in ADR-067 and
+  ADR-048; the recently landed WS robustness work — idle-read timeout,
+  session caps/eviction, pump consolidation — is the foundation the
+  deferred work builds on)
+- **Cross-references**: [ADR-067](decisions/067-websocket-carries-channels.md),
+  [ADR-048](decisions/048-websocket-native-session-not-gateway.md),
+  [websocket.md](websocket.md), tasks/websocket/review-001-ws-data-channel-decision.md
+
 ## Resolved (ported)
 
 Resolutions inherited from the alknet architecture; recorded here for