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>

opc/plugins/office_ui/frontend_src/lib/progressLog.test.ts

@@ -114,3 +114,38 @@ permissionLog = appendProgressEntry(permissionLog, {
 
 assert.equal(permissionLog.length, 1)
 assert.equal(permissionLog[0]?.summary, 'shell_exec: allow')
+
+// Native company assistant replies stream like thinking: same-stream deltas
+// accumulate into one entry instead of replacing each other, and separate
+// iterations (distinct item_id) stay separate entries.
+let assistantLog = appendProgressEntry([], {
+  timestamp: 30,
+  type: 'assistant',
+  summary: '文件已成功写入',
+  detail: '文件已成功写入',
+  turnId: 'rt-1:4',
+  itemId: 'rt-1:4:iter:2:assistant',
+  seq: 1,
+})
+assistantLog = appendProgressEntry(assistantLog, {
+  timestamp: 31,
+  type: 'assistant',
+  summary: '(278 行)。',
+  detail: '(278 行)。',
+  turnId: 'rt-1:4',
+  itemId: 'rt-1:4:iter:2:assistant',
+  seq: 2,
+})
+assistantLog = appendProgressEntry(assistantLog, {
+  timestamp: 32,
+  type: 'assistant',
+  summary: '采集完成报告',
+  detail: '采集完成报告',
+  turnId: 'rt-1:4',
+  itemId: 'rt-1:4:iter:3:assistant',
+  seq: 1,
+})
+assert.equal(assistantLog.length, 2)
+assert.equal(assistantLog[0]?.detail, '文件已成功写入(278 行)。')
+assert.equal(assistantLog[0]?.summary, '文件已成功写入(278 行)。')
+assert.equal(assistantLog[1]?.detail, '采集完成报告')