add tritanopia theme

Author: lutinglt

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

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+@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-dark-tritanopia.css

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+@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-light-tritanopia.css

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+@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;
+}