Drop classifyEvent.ts, render TermMsg directly

Per review: StreamRow was meant to match what the server sends in
TermMsg, not be a separate model needing a translation step.

- classifyEvent.ts and streamRow.ts deleted; termMsg.ts holds the wire
  types (TermMsg/TermEnvelope) plus TermRow, a TermMsg with just the
  key/fromHistory bookkeeping Preact needs for list rendering.
- Row.tsx renders a TermRow directly: level -> CSS class, empty
  summary + markdown body -> flat row, everything else with a body ->
  expandable details gated by the operator's preference. No separate
  classification step.
- useLiveStream.ts drops ClassifyCtx (a single incrementing key
  counter didn't need a whole context object) and maps envelopes to
  rows inline.
- docs/terminal-rendering.md trimmed substantially — was documenting
  more implementation detail than useful; points at stream_enrich.rs
  for the per-tool specifics instead of duplicating them in prose.

frontend/packages/agent/src/lib/termMsg.ts

@@ -0,0 +1,33 @@
+// Wire types for the agent's terminal stream — mirrors hive-agent's
+// `term_msg.rs`/`web_ui/stream.rs` field-for-field. The frontend renders
+// a `TermMsg` close to as-is (see components/Row.tsx); there's no
+// separate client-side row model or classification step any more —
+// mara: "StreamRow should now match what the server sends in TermMsg."
+export type Level = 'debug' | 'info' | 'warn' | 'error';
+
+export interface TermMsg {
+  icon?: string;
+  level: Level;
+  summary: string;
+  body?: string;
+  body_format?: 'markdown' | 'diff';
+  coalesce_key?: string;
+}
+
+/** One SSE frame / history array entry — `hive-agent`'s `TermEnvelope`.
+ * `seq` is the live per-event dedup counter (`BusEvent::seq`); absent on
+ * history-replayed envelopes, see useLiveStream.ts's backfill dance. */
+export interface TermEnvelope {
+  ts: number;
+  seq?: number;
+  msgs: TermMsg[];
+}
+
+/** A `TermMsg` plus the bookkeeping Preact needs to render a list —
+ * stable identity for coalescing/keys, and whether it came from history
+ * replay vs. the live tail. Not a separate model: everything content-wise
+ * is still exactly the wire shape. */
+export interface TermRow extends TermMsg {
+  key: string;
+  fromHistory: boolean;
+}