Trim negative-space comments per mara's review

Don't state what a function/module doesn't do and where that
happens instead — just describe what it does. Cut the "not
something this function decides" / "not affected by this" /
"not a placeholder for a later commit" asides from the doc
comments touched in the last two commits.

frontend/packages/agent/src/hooks/useLiveStream.ts

@@ -12,18 +12,9 @@
 // terminal.js's `start()`: a live envelope landing between EventSource-
 // open and the history response resolving is buffered, not dropped or
 // double-counted (`envelope.seq <= history.seq` → already covered by the
-// initial history page, drop it from the buffer). There's no per-row
-// `kind` any more to sanity-check that against — `seq` alone is the
+// initial history page, drop it from the buffer). `seq` alone is the
 // whole dedup signal, see `TermEnvelope`'s doc in hive-agent's
 // `web_ui/stream.rs`.
-//
-// The old `onLiveTurnBoundary` callback (a snappier one-off `/api/state`
-// refresh right after a live turn_start/turn_end, instead of waiting for
-// the plain poll interval) is gone with the `kind` tag it relied on to
-// spot a turn boundary — per mara's own framing that trigger is an
-// agent-state concern, not a terminal-stream one, and this stream no
-// longer has the structure to single one out. `useAgentState`'s 4s poll
-// is the only refresh path now.
 import { useEffect, useRef, useState } from 'preact/hooks';
 import type { TermEnvelope, TermRow } from '../lib/termMsg.js';