nixvim(telescope): reorganise keymaps into categories, fix leader+f => leader + ff, close telescope on esc in insert mode

nixvim/config/telescope.nix

@@ -1,37 +1,50 @@
 {
   plugins.telescope = {
     enable = true;
+    settings.defaults.mappings = {
+      i = {
+        # close telescope when escape pressed in insert mode
+        "<esc>" = "close";
+      };
+    };
     keymaps = {
+      # files
       "<leader><space>" = {
         action = "find_files";
         options = {
           desc = "Find files in current directory";
         };
       };
-      "<leader>f" = {
+      "<leader>ff" = {
         action = "find_files";
         options = {
           desc = "Find files in current directory";
         };
       };
-      "<leader>/" = {
-        action = "live_grep";
-        options = {
-          desc = "Grep (root dir)";
-        };
-      };
-      "<leader>b" = {
-        action = "buffers";
-        options = {
-          desc = "Buffer list";
-        };
-      };
       "<leader>fr" = {
         action = "oldfiles";
         options = {
           desc = "Recent files";
         };
       };
+
+      # search
+      "<leader>/" = {
+        action = "live_grep";
+        options = {
+          desc = "Grep (root dir)";
+        };
+      };
+
+      # buffers
+      "<leader>b" = {
+        action = "buffers";
+        options = {
+          desc = "Buffer list";
+        };
+      };
+
+      # lsp
       "<leader>sD" = {
         action = "diagnostics";
         options = {