Use PNG for KV memory wall figure; switch outline to inline image embeds

- Convert figs/f4b_pdsep_kv_wall.pdf to PNG via pdftoppm @ 150 DPI so
  MEETING.md and PAPER_OUTLINE.md render the figure inline on GitHub /
  any standard markdown viewer (PDF !() embeds don't render).
- PAPER_OUTLINE.md F2, F4, F6: switch from backtick code references to
  proper ![]() image embeds so the doc is actually viewable as a deck.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

MEETING.md

@@ -43,7 +43,7 @@ LMetric 56.9%、load_only 54.1%、capped 31.6% APC，远低于 79.6% 上界。23
 
 ### 静态 PD-disagg：D 侧 KV 容量墙
 
-![](figs/f4b_pdsep_kv_wall.pdf)
+![](figs/f4b_pdsep_kv_wall.png)
 
 agentic 平均请求 33.6k token 需 3.3GB KV；4P+4D / 6P+2D 在 agentic regime 都穿过 90% 内存墙。**TTFT p50 暴涨 62-72x，成功率 99.5% → 52-68%**。