fix: correct gut-microbiome-damage.jpg path in cancer.html and diabetes.html

feat: add missing reference screenshots (turmeric marketplace, nature figures)

web/articles/cancer.html

@@ -1253,7 +1253,7 @@
   <div class="evidence-title">🦠 肠道菌群与结直肠癌 — Science 2015</div>
   <img class="ref-shot" src="../img/ref-screenshots/cancer_ref4.png" alt="Fusobacterium nucleatum and colorectal cancer">
   <div class="evidence-image-wrap">
-    <img src="../img/gut-microbiome-damage.jpg" alt="Colorectal cancer - Fusobacterium nucleatum and gut microbiota" style="max-height:200px;">
+    <img src="../img/ref-screenshots/gut-microbiome-damage.jpg" alt="Colorectal cancer - Fusobacterium nucleatum and gut microbiota" style="max-height:200px;">
   </div>
   <div class="evidence-caption">
     <strong>Science 2015:</strong> Fusobacterium nucleatum（具核梭杆菌）在结直肠癌组织中富集，可通过FadA黏附素结合E-cadherin激活β-catenin信号通路，促进癌细胞的增殖和肿瘤进展。

web/articles/diabetes.html

@@ -951,7 +951,7 @@
   <div class="evidence-title">🦠 肠道菌群与2型糖尿病 — Nature 2012里程碑研究</div>
   <img class="ref-shot" src="../img/ref-screenshots/diabetes_ref3.png" alt="Gut microbiota and type 2 diabetes - Nature 2012">
   <div class="evidence-image-wrap">
-    <img src="../img/gut-microbiome-damage.jpg" alt="Gut microbiota in T2DM" style="max-height:200px;">
+    <img src="../img/ref-screenshots/gut-microbiome-damage.jpg" alt="Gut microbiota in T2DM" style="max-height:200px;">
   </div>
   <div class="evidence-caption">
     <strong>Nature 2012:</strong> 中国深圳华大基因研究院对345例中国2型糖尿病患者的宏基因组关联研究，发现T2DM患者存在中度肠道菌群失调，产丁酸细菌（如Roseburia、Faecalibacterium prausnitzii）减少，而条件致病菌增多。菌群功能基因分析显示，肠道菌群参与了T2DM的代谢调控。