feat: add snacks.nvim picker integration (#720)

Co-authored-by: Tony Fischer (tku137) <[email protected]>

lua/CopilotChat/integrations/snacks.lua

@@ -0,0 +1,53 @@
+local snacks = require('snacks')
+local chat = require('CopilotChat')
+local utils = require('CopilotChat.utils')
+
+local M = {}
+
+--- Pick an action from a list of actions
+---@param pick_actions CopilotChat.integrations.actions?: A table with the actions to pick from
+---@param opts table?: snacks options
+function M.pick(pick_actions, opts)
+  if not pick_actions or not pick_actions.actions or vim.tbl_isempty(pick_actions.actions) then
+    return
+  end
+
+  utils.return_to_normal_mode()
+  opts = vim.tbl_extend('force', {
+    items = vim.tbl_map(function(name)
+      return {
+        id = name,
+        text = name,
+        file = name,
+        preview = {
+          text = pick_actions.actions[name].prompt,
+          ft = 'text',
+        },
+      }
+    end, vim.tbl_keys(pick_actions.actions)),
+    preview = 'preview',
+    win = {
+      preview = {
+        wo = {
+          wrap = true,
+          linebreak = true,
+        },
+      },
+    },
+    title = pick_actions.prompt,
+    confirm = function(picker)
+      local selected = picker:current()
+      if selected then
+        local action = pick_actions.actions[selected.id]
+        vim.defer_fn(function()
+          chat.ask(action.prompt, action)
+        end, 100)
+      end
+      picker:close()
+    end,
+  }, opts or {})
+
+  snacks.picker(opts)
+end
+
+return M