feat(picker): make register picker list more informative

This commit
- adds separate hightlighting for different register types (numbered,
  named, other)
- adds a hint about the register type (characterwise, linewise,
  blockwise) similar to the builtin :reg command

lua/snacks/picker/config/highlights.lua

@@ -38,7 +38,9 @@ Snacks.util.set_hl({
   AuGroup = "Type",
   DiagnosticCode = "Special",
   DiagnosticSource = "Comment",
-  Register = "Number",
+  RegisterNumber = "Number",
+  RegisterOther = "Constant",
+  RegisterString = "String",
   KeymapMode = "Number",
   KeymapLhs = "Special",
   KeymapNowait = "@variable.builtin",

lua/snacks/picker/format.lua

@@ -596,11 +596,14 @@ end
 
 function M.register(item)
   local ret = {} ---@type snacks.picker.Highlight[]
+  local hl = string.match(item.reg, "[0-9]") and "Number" or string.match(item.reg, "[a-z]") and "String" or "Other"
   ret[#ret + 1] = { " " }
   ret[#ret + 1] = { "[", "SnacksPickerDelim" }
-  ret[#ret + 1] = { item.reg, "SnacksPickerRegister" }
+  ret[#ret + 1] = { item.reg, "SnacksPickerRegister" .. hl }
   ret[#ret + 1] = { "]", "SnacksPickerDelim" }
   ret[#ret + 1] = { " " }
+  ret[#ret + 1] = { item.type, "Comment" }
+  ret[#ret + 1] = { " " }
   ret[#ret + 1] = { item.value }
   return ret
 end

lua/snacks/picker/source/vim.lua

@@ -273,11 +273,14 @@ function M.registers()
       value = (ok and reg_value or "") --[[@as string]]
     end
     if value ~= "" then
+      local type = vim.fn.getregtype(reg)
+      type = type == "v" and "c" or type == "V" and "l" or "b:" .. type:sub(2)
       table.insert(items, {
         text = ("%s: %s"):format(reg, value:gsub("\n", "\\n"):gsub("\r", "\\r")),
         reg = reg,
         label = reg,
         data = value,
+        type = type,
         value = value:gsub("\n", "\\n"):gsub("\r", "\\r"),
         preview = {
           text = value,