docs: thêm màu vào Mermaid pipeline diagrams

README.md

@@ -33,6 +33,12 @@ Hệ thống RAG (Retrieval-Augmented Generation) cho tài liệu tài chính ti
 
 ```mermaid
 flowchart TD
+    classDef doc     fill:#dbeafe,stroke:#3b82f6,color:#1e40af,font-weight:bold
+    classDef process fill:#dcfce7,stroke:#16a34a,color:#14532d
+    classDef store   fill:#fef3c7,stroke:#d97706,color:#92400e,font-weight:bold
+    classDef ai      fill:#f3e8ff,stroke:#9333ea,color:#581c87,font-weight:bold
+    classDef output  fill:#ccfbf1,stroke:#0d9488,color:#134e4a,font-weight:bold
+
     subgraph INGEST["📥 Ingest (Offline)"]
         A["Tài liệu PDF / Ảnh"] --> B["Parser\npypdf / EasyOCR"]
         B --> C["Chunker"]
@@ -56,12 +62,26 @@ flowchart TD
         RE --> LLM["LLM · Groq\nllama-3.3-70b-versatile"]
         LLM --> ANS["Câu trả lời + Trích dẫn"]
     end
+
+    class A doc
+    class B,C process
+    class CR,EMB,QR,QE,RE,LLM ai
+    class VDB,BM25 store
+    class VS,BS,RRF process
+    class Q doc
+    class ANS output
 ```
 
 ### Pipeline B — ColPali Visual Retrieval (thực nghiệm so sánh)
 
 ```mermaid
 flowchart TD
+    classDef doc     fill:#dbeafe,stroke:#3b82f6,color:#1e40af,font-weight:bold
+    classDef process fill:#dcfce7,stroke:#16a34a,color:#14532d
+    classDef store   fill:#fef3c7,stroke:#d97706,color:#92400e,font-weight:bold
+    classDef ai      fill:#f3e8ff,stroke:#9333ea,color:#581c87,font-weight:bold
+    classDef output  fill:#ccfbf1,stroke:#0d9488,color:#134e4a,font-weight:bold
+
     subgraph INGEST["📥 Ingest (Offline)"]
         A["Trang PDF"] --> B["Render ảnh\npypdfium2 · DPI=100"]
         B --> C["ColPali v1.2\nPaliGemma + LoRA · 128-dim patches"]
@@ -74,6 +94,12 @@ flowchart TD
         QE --> S
         S --> R["Top-k trang PDF"]
     end
+
+    class A,Q doc
+    class B,S process
+    class C,QE ai
+    class D store
+    class R output
 ```
 
 ## Công nghệ sử dụng