docs: add architecture diagrams (Mermaid + Archify map) for pi-dashboard

- docs/pi-dashboard.mmd — Mermaid source of truth
- docs/diagrams/pi-dashboard.png|svg — rendered via mmdc (mermaid-cli 11.16.0)
- docs/archify/pi-dashboard.architecture.json — Archify JSON IR
- docs/pi-dashboard-map.html — interactive map (9/9 showcase checks)
- docs/README.md — embedded mermaid + artifact index + regenerate commands
- visual-check screenshots/evidence at 1440x900 + 2048x1320 (light/dark)

Generated by project-diagramming-mermaid + project-diagramming-archify skills.

docs/pi-dashboard.mmd

@@ -0,0 +1,12 @@
+flowchart LR
+  EXT[dashboard.ts pi extension] -->|writes JSON| SF[(state files<br/>~/.pi/agent/dashboard)]
+  REM[remote machines .13 .51] -->|ssh cat *.json<br/>5s timeout + cooldown| ST[state.go]
+  SF -->|readLocalStates| ST
+  ST -->|AgentState| MAIN[main.go bubbletea TUI]
+  CFG[pi-dashboard.yaml] -->|loadConfig| MAIN
+  MAIN -->|2s poll tick| ST
+  MAIN -->|table + detail| UI[Table + Detail panes]
+  UI -->|Enter| AT[tmux / zellij attach]
+  UI -->|d| HK[hunk diff]
+  UI -->|Tab| TX[tuxedo todo.txt]
+  UI -->|Del| SF