feat: add ignore_files option

chatgpt_config.yaml

@@ -3,6 +3,11 @@ default_prompt_blocks:
   - "basic"
   - "secure-coding"
 
+ignore_files:
+  - "node_modules/"
+  - "*.log"
+  - "vendor/"
+
 include_file_contents: true
 
 debug: false

lua/chatgpt_nvim/context.lua

@@ -131,6 +131,11 @@ end
 function M.get_project_files(directories, conf)
   local root = vim.fn.getcwd()
   local ignore_patterns = load_gitignore_patterns(root, conf)
+  if conf.ignore_files then
+    for _, pattern in ipairs(conf.ignore_files) do
+      table.insert(ignore_patterns, gitignore_to_lua_pattern(pattern))
+    end
+  end
   local all_files = {}
   for _, dir in ipairs(directories) do
     local abs_dir = dir