feat(spec): first version for architecture

docs/docs/docs/specs/architecture.md

@@ -0,0 +1,40 @@
+---
+title: "Architecture and Concepts"
+---
+
+## Concepts
+```mermaid
+graph LR
+    A1[("A User Integrators")] -->|uses| B1[assistant]
+    B1 -->|persist conversational history| C1[("thread A")]
+    B1 -->|executes| D1[("built-in tools as module")]
+    B1 -.->|uses| E1[model]
+    E1 -.->|model.json| D1
+    D1 --> F1[retrieval]
+    F1 -->|belongs to| G1[("web browsing")]
+    G1 --> H1[Google]
+    G1 --> H2[Duckduckgo]
+    F1 -->|belongs to| I1[("API calling")]
+    F1 --> J1[("knowledge files")]
+```
+- User/ Integrator
+- Assistant object
+- Model object
+- Thread object
+- Built-in tool object
+
+## File system
+```sh
+janroot/
+	assistants/
+		assistant-a/
+			assistant.json
+			src/
+				index.ts
+			threads/
+				thread-a/
+				thread-b
+	models/
+		model-a/
+			model.json
+```