docs: adjust Mermaid chart styling

Co-authored-by: copilot-swe-agent[bot]
  <198982749+Copilot@users.noreply.github.com>

Author: nanotaboada

Dockerfile

@@ -45,7 +45,6 @@ COPY --from=builder     /app/publish/               .
 
 # Copy metadata docs for container registries (e.g.: GitHub Container Registry)
 COPY --chmod=444        README.md                   ./
-COPY --chmod=555        assets/                     ./assets/
 
 # https://rules.sonarsource.com/docker/RSPEC-6504/
 

README.md

@@ -98,33 +98,75 @@ test/Dotnet.Samples.AspNetCore.WebApi.Tests/
 Dependencies flow from data layer through repositories and services to controllers. External dependencies (AutoMapper, FluentValidation, Serilog) integrate at their respective layers.
 
 ```mermaid
-%%{init: {'theme':'base'}}%%
-graph TD
-    Data[Data]:::core --> Models[Models]:::core
-    Models --> Repositories[Repositories]:::core
-    Repositories --> Services[Services]:::core
-    Services --> Controllers[Controllers]:::core
-    Controllers --> Program[Program]:::core
-
-    Validators[Validators]:::core --> Controllers
-    Mappings[Mappings]:::core --> Services
-
-    AutoMapper[AutoMapper]:::external --> Mappings
-    FluentValidation[FluentValidation]:::external --> Validators
-    Serilog[Serilog]:::external --> Program
-
-    Configurations[Configurations]:::infrastructure --> Program
-    SwaggerUI[SwaggerUI]:::infrastructure --> Controllers
-    MemoryCache[MemoryCache]:::infrastructure --> Services
-    Migrations[Migrations]:::infrastructure --> Repositories
-
-    Controllers --> Tests[Tests]:::testing
-    Services --> Tests
-
-    classDef core fill:#cfe4ff,stroke:#333333,stroke-width:2px,color:#000
-    classDef external fill:#ffd9d9,stroke:#333333,stroke-width:2px,color:#000
-    classDef infrastructure fill:#fcfcca,stroke:#333333,stroke-width:2px,color:#000
-    classDef testing fill:#c3f7c8,stroke:#333333,stroke-width:2px,color:#000
+%%{init: {
+  "theme": "default",
+  "themeVariables": {
+    "fontFamily": "Fira Code, Consolas, monospace",
+    "textColor": "#555",
+    "lineColor": "#555",
+    "lineWidth": 2
+  }
+}}%%
+graph LR
+    %% Core Modules
+    Data[Data]
+    Models[Models]
+    Repositories[Repositories]
+    Services[Services]
+    Controllers[Controllers]
+    Program[Program]
+    Validators[Validators]
+    Mappings[Mappings]
+
+    %% External Dependencies
+    AutoMapper[AutoMapper]
+    FluentValidation[FluentValidation]
+    Serilog[Serilog]
+
+    %% Supporting Features
+    Configurations[Configurations]
+    SwaggerUI[SwaggerUI]
+    MemoryCache[MemoryCache]
+    Migrations[Migrations]
+
+    %% Tests
+    Tests[Tests]
+
+    %% Main Application Flow
+    Data --> Models
+    Models --> Repositories
+    Repositories --> Services
+    Services --> Controllers
+    Controllers --> Program
+
+    Validators --> Controllers
+    Mappings --> Services
+
+    %% External Dependencies connections
+    AutoMapper --> Mappings
+    FluentValidation --> Validators
+    Serilog --> Program
+
+    %% Supporting Features connections
+    Configurations --> Program
+    SwaggerUI --> Controllers
+    MemoryCache --> Services
+    Migrations --> Repositories
+
+    %% Tests connections
+    Controllers -.-> Tests
+    Services -.-> Tests
+
+    %% Node styling (fallbacks)
+    classDef core fill:#b3d9ff,stroke:#6db1ff,stroke-width:2px,color:#555,font-family:monospace;
+    classDef deps fill:#ffcccc,stroke:#ff8f8f,stroke-width:2px,color:#555,font-family:monospace;
+    classDef test fill:#ccffcc,stroke:#53c45e,stroke-width:2px,color:#555,font-family:monospace;
+    classDef feat fill:#ffffcc,stroke:#fdce15,stroke-width:2px,color:#555,font-family:monospace;
+
+    class Data,Models,Repositories,Services,Controllers,Program,Validators,Mappings core;
+    class AutoMapper,FluentValidation,Serilog deps;
+    class Tests test;
+    class Configurations,SwaggerUI,MemoryCache,Migrations feat;
 ```
 
 *Layered architecture: Core application flow (blue), supporting features (yellow), external dependencies (red), and test coverage (green). Not all dependencies are shown.*