fix: binding shortcuts to specific buffers (#238)

lua/avante/utils/buf_storage.lua

@@ -0,0 +1,34 @@
+-- Copy from: https://github.com/MunifTanjim/nui.nvim/blob/main/lua/nui/utils/buf_storage.lua
+local utils = require("avante.utils")
+
+local buf_storage = {
+  _registry = {},
+}
+
+---@param storage_name string
+---@param default_value any
+---@return table<number, any>
+function buf_storage.create(storage_name, default_value)
+  local storage = setmetatable({}, {
+    __index = function(tbl, bufnr)
+      rawset(tbl, bufnr, vim.deepcopy(utils.fallback(default_value, {})))
+
+      -- TODO: can `buf_storage.cleanup` be automatically (and reliably) triggered on `BufWipeout`?
+
+      return tbl[bufnr]
+    end,
+  })
+
+  buf_storage._registry[storage_name] = storage
+
+  return storage
+end
+
+---@param bufnr number
+function buf_storage.cleanup(bufnr)
+  for _, storage in pairs(buf_storage._registry) do
+    rawset(storage, bufnr, nil)
+  end
+end
+
+return buf_storage