fix(office-ui): stop progress-row flicker and surface native role replies end to end

Two user-visible defects in company mode, root-caused via project 6666/8888
DB forensics:

Progress-row flicker (thinking preview appearing/disappearing): progress
entries were broadcast to clients before reaching the persistence buffer,
so a tool_call-triggered session_detail snapshot rebuilt from the DB erased
freshly streamed entries from the live log. Buffer now fills before the
broadcast and session_detail flushes it before reading.

Native role transcripts incomplete (thinking only at start, no narration,
no final summary — external agents unaffected):
- thinking deltas shared one stream id per conversation turn while seq
  reset per iteration, collapsing all iterations into one entry and
  silently dropping live thinking from iteration 2 on; now keyed per
  iteration like assistant deltas
- assistant_delta events were mapped to None; company mode now surfaces
  them as streaming 'assistant' progress entries (rendered as Reply cards,
  merged like thinking, excluded from inline chat rows)
- thinking was persisted one row per token, flooding the 1000-entry cap
  and evicting interleaved tool history; append_progress now folds
  streaming deltas per (type, turn, stream) with seq dedup
- the terminal company turn was hidden at summary detail and, worse, its
  id-keyed backfill merge kept the first-inserted intermediate content, so
  the final reply never reached any channel; terminal turns are now
  flagged company_final_turn, visible at summary detail, and carry their
  own ui_message_id so they insert as fresh rows
- appendProgressEntry applied its seq guard against unrelated entries when
  the stream key was absent from the log, killing the first delta of any
  fresh stream; the guard now only applies within the same stream

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_native_runtime_v2.py

@@ -409,9 +409,31 @@ class NativeRuntimeV2Tests(unittest.IsolatedAsyncioTestCase):
         self.assertEqual(metadata["execution_mode"], "company_mode")
         self.assertTrue(metadata["company_runtime_raw_turn"])
         self.assertEqual(metadata["role_id"], "chao")
-        self.assertEqual(metadata["ui_message_id"], "runtime-v2-company-assistant:ui-turn:company")
+        # No tool calls ⇒ terminal iteration: flagged as the role's final
+        # reply and given its own UI row id so the id-keyed backfill merge
+        # cannot swallow it into the frozen shared-iteration row.
+        self.assertTrue(metadata["company_final_turn"])
+        self.assertEqual(metadata["ui_message_id"], "runtime-v2-company-assistant-final:ui-turn:company")
         self.assertNotIn("visible_speaker", metadata)
 
+        await runtime._persist_assistant_turn(
+            task,
+            "中间轮叙述",
+            [{"id": "call-1", "function": "file_read", "arguments": {}}],
+            runtime_session_id="rt_company",
+            turn_id="ui-turn:company:iter:1",
+            conversation_turn_id="ui-turn:company",
+            iteration=1,
+        )
+
+        intermediate_metadata = memory.appended_messages[-1]["kwargs"]["metadata"]
+        self.assertEqual(intermediate_metadata["kind"], "runtime_v2_company_assistant")
+        self.assertNotIn("company_final_turn", intermediate_metadata)
+        self.assertEqual(
+            intermediate_metadata["ui_message_id"],
+            "runtime-v2-company-assistant:ui-turn:company",
+        )
+
     async def test_task_mode_assistant_turn_with_company_defaults_stays_opc_task_reply(self) -> None:
         memory = _StubMemoryManager(_StubStore())
         runtime = NativeRuntimeV2(