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/chat/AgentProgressBlock.tsx

@@ -18,6 +18,7 @@ export const INLINE_PROGRESS_ENTRY_TYPES = new Set<ProgressEntryType>(['thinking
 
 const ENTRY_CONFIG: Record<ProgressEntryType, { icon: React.ReactNode; color: string; label: string }> = {
   thinking:      { icon: <IconBrain />,       color: 'var(--accent)',          label: 'Thinking' },
+  assistant:     { icon: <IconSparkle />,     color: 'var(--accent)',          label: 'Reply' },
   tool_call:     { icon: <IconTool />,        color: 'var(--green)',           label: 'Tool' },
   autonomy:      { icon: <IconShield />,      color: 'var(--yellow)',          label: 'Autonomy' },
   handoff:       { icon: <IconArrowRight />,  color: 'var(--accent)',          label: 'Handoff' },
@@ -257,7 +258,7 @@ export const AgentProgressEntryCard = React.memo(function AgentProgressEntryCard
     )
   }
 
-  if (entry.type === 'thinking') {
+  if (entry.type === 'thinking' || entry.type === 'assistant') {
     return (
       <div className="ptl-tool-card">
         <button