docs: rename DEVELOPMENT.md to development.md and update links

- Rename docs/contributing/DEVELOPMENT.md to development.md (lowercase)
- Update all references from DEVELOPMENT.md to Development.md (titlecase links)
- Update docs/contributing/contributing.md
- Update docs/index.md

web/static/input.css

@@ -16,8 +16,8 @@
   .theme-tokyo-night {
     --bg-primary: #1a1b26;
     --bg-secondary: #16161e;
-    --text-primary: #a9b1d6;
-    --text-secondary: #9aa5ce;
+    --text-primary: #c0caf5;
+    --text-secondary: #c0caf5;
     --accent: #7aa2f7;
     --border: #414868;
   }