feat: add Poimen Memory deep dive page at /poimen/memory

- Architecture, dataflow, and sequence diagrams (700px iframes)
- Three-tier retrieval section (signature match, graph-boosted, Obsidian)
- Technology stack grid (Rust, pgvector, TEI, Authentik, etc.)
- Wire deepDive link from Memory project card
- Add Poimen timeline card to ExperienceTimeline

app/page.tsx

@@ -29,7 +29,9 @@ export default function Home() {
         : undefined,
     videoUrl: '#',
     articleUrl: index === 4 ? 'https://lnkd.in/p/gm2PZkWw' : '#',
-    deepDive: index === 2 ? { url: '/homelab', label: 'Explore the Architecture →' } : undefined,
+    deepDive: index === 2 ? { url: '/homelab', label: 'Explore the Architecture →' }
+      : index === 1 ? { url: '/poimen/memory', label: 'Explore the Memory System →' }
+      : undefined,
     ciRepos: index === 0 ? [
       { label: 'poimen-wf', repo: 'riotpiao-poimen/poimen-workflows', forgejoBase: 'https://forgejo.riotpiao.com/riotpiao-poimen/poimen-workflows' },
     ] : index === 1 ? [