Replace ASCII diagram with Mermaid flowchart

ASCII box alignment is fragile across renderers. Mermaid renders
natively in MkDocs Material and stays correct at any width.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: KI7MT

docs/architecture.md

@@ -6,39 +6,38 @@
 
 ## System Overview
 
-```
-┌───────────────────────────────────────────────────────┐
-│                     AI Assistant                      │
-│          Claude · ChatGPT · Cursor · Gemini           │
-└───────────────────────────┬───────────────────────────┘
-                            │ MCP Protocol (stdio)
-                            ▼
-┌───────────────────────────────────────────────────────┐
-│                   MCP Servers (local)                  │
-│                                                       │
-│  ┌──────────┐ ┌─────────┐ ┌─────────┐ ┌──────────┐  │
-│  │ eqsl-mcp │ │ qrz-mcp │ │lotw-mcp │ │ pota-mcp │  │
-│  └─────┬────┘ └────┬────┘ └────┬────┘ └─────┬────┘  │
-│        │           │           │             │       │
-│  ┌─────┴───────────┴───────────┴─────────────┘       │
-│  │                                                   │
-│  │  adif-mcp (foundation)                            │
-│  │  ├── PersonaManager → OS Keyring                  │
-│  │  ├── ADIF 3.1.6 Spec (186 fields, 25 enums)      │
-│  │  ├── Validation Engine                            │
-│  │  └── Geospatial (distance, heading)               │
-│  │                                                   │
-│  └───────────────────────────────────────────────────┘
-│                                                       │
-└───────────────────────────────────────────────────────┘
-                            │ HTTPS only
-                            ▼
-┌───────────────────────────────────────────────────────┐
-│                   External Services                   │
-│                                                       │
-│   eQSL.cc · QRZ.com · LoTW · Club Log · HamQTH       │
-│   POTA · SOTA · NOAA SWPC · WSPR Network              │
-└───────────────────────────────────────────────────────┘
+```mermaid
+graph TD
+    AI["<b>AI Assistant</b><br/>Claude · ChatGPT · Cursor · Gemini"]
+    AI -->|"MCP Protocol (stdio)"| Servers
+
+    subgraph Servers["MCP Servers (local)"]
+        direction TB
+        eqsl["eqsl-mcp"]
+        qrz["qrz-mcp"]
+        lotw["lotw-mcp"]
+        clublog["clublog-mcp"]
+        hamqth["hamqth-mcp"]
+        pota["pota-mcp"]
+        sota["sota-mcp"]
+        solar["solar-mcp"]
+        wspr["wspr-mcp"]
+
+        subgraph Foundation["adif-mcp (foundation)"]
+            persona["PersonaManager → OS Keyring"]
+            spec["ADIF 3.1.6 Spec (186 fields, 25 enums)"]
+            valid["Validation Engine"]
+            geo["Geospatial (distance, heading)"]
+        end
+
+        eqsl & qrz & lotw & clublog & hamqth --> Foundation
+    end
+
+    Servers -->|"HTTPS only"| Services
+
+    subgraph Services["External Services"]
+        svc["eQSL.cc · QRZ.com · LoTW · Club Log · HamQTH<br/>POTA · SOTA · NOAA SWPC · WSPR Network"]
+    end
 ```
 
 ---

mkdocs.yml

@@ -35,7 +35,11 @@ markdown_extensions:
   - admonition
   - pymdownx.highlight:
       anchor_linenums: true
-  - pymdownx.superfences
+  - pymdownx.superfences:
+      custom_fences:
+        - name: mermaid
+          class: mermaid
+          format: !!python/name:pymdownx.superfences.fence_code_format
   - pymdownx.details
   - pymdownx.tabbed:
       alternate_style: true