Support blue yellow colorblind theme (#35910)

This icon is from GitHub:

<img width="350" height="350" alt="image"
src="https://github.com/user-attachments/assets/c3f31901-5359-4b7f-ae68-eddcec63df53"
/>

---------

Signed-off-by: 鲁汀 <131967983+lutinglt@users.noreply.github.com>
Co-authored-by: lutinglt <lutinglt@users.noreply.github.com>

Author: lutinglt

public/assets/img/svg/gitea-colorblind-blueyellow.svg

@@ -39,13 +39,19 @@ func (info *ThemeMetaInfo) GetDescription() string {
 	if info.ColorblindType == "red-green" {
 		return "Red-green colorblind friendly"
 	}
+	if info.ColorblindType == "blue-yellow" {
+		return "Blue-yellow colorblind friendly"
+	}
 	return ""
 }
 
 func (info *ThemeMetaInfo) GetExtraIconName() string {
 	if info.ColorblindType == "red-green" {
 		return "gitea-colorblind-redgreen"
 	}
+	if info.ColorblindType == "blue-yellow" {
+		return "gitea-colorblind-blueyellow"
+	}
 	return ""
 }
 

services/webtheme/webtheme.go

@@ -0,0 +1,8 @@
+@import "./theme-gitea-light-tritanopia.css" (prefers-color-scheme: light);
+@import "./theme-gitea-dark-tritanopia.css" (prefers-color-scheme: dark);
+
+gitea-theme-meta-info {
+  --theme-display-name: "Auto";
+  --theme-colorblind-type: "blue-yellow";
+  --theme-color-scheme: "auto";
+}

web_src/css/themes/theme-gitea-auto-tritanopia.css

@@ -0,0 +1,15 @@
+@import "./theme-gitea-dark-protanopia-deuteranopia.css";
+
+gitea-theme-meta-info {
+  --theme-display-name: "Dark";
+  --theme-colorblind-type: "blue-yellow";
+  --theme-color-scheme: "dark";
+}
+
+/* blue/yellow colorblind-friendly colors */
+/* from GitHub: blue yellow blindness is based on red green blindness, and --diffBlob-deletion-* restored to the normal theme color */
+:root {
+  --color-diff-removed-linenum-bg: #482121;
+  --color-diff-removed-row-bg: #301e1e;
+  --color-diff-removed-word-bg: #6f3333;
+}

web_src/css/themes/theme-gitea-dark-tritanopia.css

@@ -0,0 +1,15 @@
+@import "./theme-gitea-light-protanopia-deuteranopia.css";
+
+gitea-theme-meta-info {
+  --theme-display-name: "Light";
+  --theme-colorblind-type: "blue-yellow";
+  --theme-color-scheme: "light";
+}
+
+/* blue/yellow colorblind-friendly colors */
+/* from GitHub: blue yellow blindness is based on red green blindness, and --diffBlob-deletion-* restored to the normal theme color */
+:root {
+  --color-diff-removed-linenum-bg: #ffcecb;
+  --color-diff-removed-row-bg: #ffeef0;
+  --color-diff-removed-word-bg: #fdb8c0;
+}