fix(config): normalize channel streaming config shape (#61381)

* feat(config): add canonical streaming config helpers

* refactor(runtime): prefer canonical streaming accessors

* feat(config): normalize preview channel streaming shape

* test(config): lock streaming normalization followups

* fix(config): polish streaming migration edges

* chore(config): refresh streaming baseline hash

scripts/lib/plugin-sdk-entrypoints.json

@@ -13,6 +13,7 @@
   "setup-adapter-runtime",
   "setup-runtime",
   "channel-setup",
+  "channel-streaming",
   "setup-tools",
   "approval-auth-runtime",
   "approval-client-runtime",