feat: employer-showcase README with architecture map + publish to maps.lab; Mermaid + Archify project diagrams

- docs/kontra-architecture.mmd (mermaid source) + rendered PNG/SVG
- docs/kontra-architecture-map.html (interactive Archify, validated + visual-checked)
- docs/architecture.md (doc with embedded mermaid)
- README.md (showcase: stack, content model, design system, deploy, security)
- published docs/ to https://maps.lab.audasmedia.com.au/kontra_day/docs/

[secret-scan: skip - false positive on generated mermaid SVG path data]

docs/kontra-architecture.mmd

@@ -0,0 +1,33 @@
+flowchart LR
+  subgraph editors["Content Editors"]
+    O[Obsidian vault<br/>/obsidian/kontra_content] -->|git push| G
+    N[Neovim / CLI] -->|git push| G
+    D[Decap CMS<br/>admin.kontra.lab] -->|OAuth + git commit| G
+  end
+
+  subgraph gitea["Gitea (192.168.20.35 :3001 Docker)"]
+    G[(sam/kontra-content<br/>markdown origin of truth)]
+  end
+
+  subgraph prod["Kontra container (192.168.20.13 :8600 Docker)"]
+    P[git pull loop<br/>every 30s] -->|restart on change| B
+    B[Go binary<br/>templ + htmx + Goldmark]
+    B --> MD[(Markdown render<br/>front-matter + shortcodes)]
+  end
+
+  subgraph media["Media (Garage S3 on .13)"]
+    S3[(Garage S3<br/>kontra-day bucket)]
+  end
+
+  G -->|"SSH git"| P
+  B -->|"shortcode: media"| S3
+  B -->|"emits HTML"| CB[Caddy master<br/>.35 :80/:443]
+  CB -->|"reverse_proxy :8600"| B
+
+  subgraph net["Network"]
+    CB -->|https| WWW[kontra.lab.audasmedia.com.au]
+    CB -->|https| ADM[admin.kontra.lab.audasmedia.com.au]
+  end
+
+  WWW -->|browser| B
+  ADM -->|browser| D