docs(Common): Improve Mermaid diagram styling and consistency

Updated the Mermaid diagram in the README to use capitalized class names (e.g., 'Mountain', 'Common') for consistency and improved the labeling by using backticks for code elements and the crate name. This enhances the diagram's readability and aligns with the project's documentation standards, ensuring clear communication of the `Common` crate's architecture and its relationship with consumers like `Mountain`. The changes maintain the core representation of:

1. The abstract traits (`FileSystemReader`), `ActionEffects`, and DTOs defined in `Common`
2. The dependency relationship between Effects and Traits
3. `Mountain`'s role as the primary implementer of `Common` traits
4. Test consumers' relationship to the core architecture

This documentation refinement follows recent refactoring work on effect dependencies (5adcc5e) and architecture updates (926b00c).

Author: NikolaRHristov

README.md

@@ -148,22 +148,22 @@ it.
 
 ```mermaid
 graph LR
-    classDef mountain fill:#f9f,stroke:#333,stroke-width:2px;
-    classDef common fill:#cfc,stroke:#333,stroke-width:1px;
-    classDef consumer fill:#9cf,stroke:#333,stroke-width:2px;
+    classDef Mountain fill:#f9f,stroke:#333,stroke-width:2px;
+    classDef Common fill:#cfc,stroke:#333,stroke-width:1px;
+    classDef Consumer fill:#9cf,stroke:#333,stroke-width:2px;
 
-    subgraph "The `Common` Crate"
+    subgraph "The \`Common\` Crate"
         direction LR
-        Traits["Abstract Traits (e.g., `FileSystemReader`)"]:::common
-        Effects["ActionEffects (e.g., `ReadFile`)"]:::common
-        DTOs["Data Transfer Objects (e.g., `FileTypeDTO`)"]:::common
+        Traits["Abstract Traits (e.g., \`FileSystemReader\`)"]:::Common
+        Effects["ActionEffects (e.g., \`ReadFile\`)"]:::Common
+        DTOs["Data Transfer Objects (e.g., \`FileTypeDTO\`)"]:::Common
 
         Effects -- Depend on --> Traits
     end
 
     subgraph "Consumers"
-        Mountain[**Mountain Application**]:::mountain
-        Tests[Unit & Integration Tests]:::consumer
+        Mountain[**Mountain Application**]:::Mountain
+        Tests[Unit & Integration Tests]:::Consumer
     end
 
     Mountain -- Implements --> Traits