feat: VSCode 风格 Neovim 配置

- 分层架构：config/{options,keymaps,lazy} + plugins/
- 保留：blink.cmp, oil.nvim, runner.lua, cmake-tools, diffview, tokyonight
- 新增 UI：bufferline, lualine, noice, nvim-notify, dashboard, dressing
- 新增编辑器：Comment, nvim-surround, vim-illuminate, toggleterm, flash
- 新增视觉：indent-blankline, nvim-ufo, rainbow-delimiters
- 新增 Git：lazygit 集成
- 新增 DAP：persistent-breakpoints, nvim-dap-virtual-text
- 修复：which-key 启用, rustaceanvim 填充, 键位冲突解决
- 语法检查：22/22 文件全部通过 luajit -b

lua/plugins/whichkey.lua

@@ -0,0 +1,65 @@
+-- =============================================================================
+-- whichkey.lua — 键位提示
+-- =============================================================================
+-- 【修复】原配置 enabled = false 直接禁用了，现在启用。
+-- 【修改】🔧 enabled 改为 true；
+--         🔧 更完善的分组和图标配置。
+
+return {
+  {
+    "folke/which-key.nvim",
+    event = "VeryLazy",
+    opts = {
+      preset = "modern",
+      delay = 200,
+      icons = {
+        breadcrumb = "»",
+        separator  = "➜",
+        group      = "+",
+      },
+      win = {
+        border = "rounded",
+        padding = { 1, 1 },
+        wo = { winblend = 0 },
+      },
+      plugins = {
+        spelling = { enabled = true, suggestions = 20 },
+        presets = {
+          operators = false,
+          motions = false,
+          text_objects = false,
+          windows = false,
+          nav = false,
+          z = true,
+          g = true,
+        },
+      },
+    },
+    config = function(_, opts)
+      local wk = require("which-key")
+      wk.setup(opts)
+
+      -- ✅ 新增：键位分组提示
+      wk.add({
+        { "<leader>f", group = "搜索" },
+        { "<leader>g", group = "Git" },
+        { "<leader>h", group = "Hunk 操作" },
+        { "<leader>l", group = "LSP" },
+        { "<leader>r", group = "运行/调试" },
+        { "<leader>c", group = "CMake/C++" },
+        { "<leader>b",  group = "标签操作" },
+        { "<leader>bc", desc = "关闭标签" },
+        { "<leader>bo", desc = "关闭其他标签" },
+        { "<leader>d",  group = "调试操作" },
+        { "<leader>db", desc = "切换断点" },
+        { "<leader>du", desc = "调试界面" },
+        { "<leader>dd", desc = "行诊断" },
+        { "<leader>W", group = "窗口操作" },
+        { "<leader>e", group = "文件浏览" },
+        { "z", group = "折叠" },
+        { "zM", desc = "关闭所有折叠" },
+        { "zR", desc = "展开所有折叠" },
+      })
+    end,
+  },
+}