docs(agent): point the streaming reader at session/event assistant/chunk

Follow-up to the README fix: the dsh-agent README's emit section had lost its
streaming entry, leaving a "Streaming + tool" heading with no pointer to where
the token stream now lives. Rename the section to "Live control notifications"
and add a line directing readers to the durable `session/event` `assistant/chunk`
feed.

packages/core/agent/README.md

@@ -50,11 +50,13 @@ Turn and step boundaries are NOT mirrored as `agent/*` emits: a consumer that ne
 
 Tool interception is the `tools/pre-execute` / `tools/post-execute` pair in [`dsh-tools`](../tools/README.md) (`PreToolDecision` allow/deny/ask, `PostToolDecision` accept/block) — same typed-Decision idiom, owned there because it is the tool registry's seam.
 
-#### Streaming + tool (emit)
+#### Live control notifications (emit)
 
 - `agent/steering` — steering content injected mid-turn
 - `agent/error` — step/turn error
 
+The model's token stream is NOT an `agent/*` event: read it off the durable `session/event` feed as `assistant/chunk` (the same feed persistence and the ACP bridge use).
+
 ### Agent interface (`types.ts`)
 
 The handle every plugin programs against: