Update service ports in documentation and configuration files to 12000 for backend

docs/7-deployment-view.md

@@ -13,7 +13,7 @@ Describes:
 │  ┌─────────────┐  ┌─────────────────────┐   │
 │  │  frontend   │  │      backend        │   │
 │  │  (Flask)    │  │    (FastAPI)        │   │
-│  │  :5000      │  │    :8000            │   │
+│  │  :5000      │  │    :12000            │   │
 │  └──────┬──────┘  └──────────┬──────────┘   │
 │         │                   │              │
 │         └────────┬──────────┘              │
@@ -31,11 +31,11 @@ Describes:
 
 **Mapping of Building Blocks to Infrastructure:**
 
-| Building Block  | Container / Process          | Port |
-| --------------- | ---------------------------- | ---- |
-| Flask frontend  | `frontend`                   | 5000 |
-| FastAPI backend | `backend`                    | 8000 |
-| DuckDB          | File on host (`data/app.db`) | —    |
+| Building Block  | Container / Process          | Port  |
+| --------------- | ---------------------------- | ----- |
+| Flask frontend  | `frontend`                   | 5000  |
+| FastAPI backend | `backend`                    | 12000 |
+| DuckDB          | File on host (`data/app.db`) | —     |
 
 ## Infrastructure Level 2