Add LSP diagnostic backgrounds for better visibility

Introduce light tinted backgrounds for LSP diagnostics
to enhance code highlighting and improve user experience.

lua/settings.lua

@@ -56,15 +56,8 @@ vim.diagnostic.config({
       return string.format("%s: %s", diagnostic.source or "", diagnostic.message)
     end,
   },
-  signs = {
-    text = {
-      [vim.diagnostic.severity.ERROR] = "E",
-      [vim.diagnostic.severity.WARN] = "W",
-      [vim.diagnostic.severity.HINT] = "H",
-      [vim.diagnostic.severity.INFO] = "I",
-    },
-  },
-  underline = true,          -- Underline problematic text
+  signs = false,             -- Disable signs (redundant with background highlights and virtual text)
+  underline = true,          -- Use background highlights on problematic text
   update_in_insert = false,  -- Don't update diagnostics while typing
   severity_sort = true,      -- Sort by severity (errors first)
   float = {