feat: add Harpoon and Training mode plugins

- Add Harpoon for quick file navigation
- Add Training mode for learning vim motions without crutches
- Configure keymaps for both plugins
- Add Nix integration for training mode toggle

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

lua/plugins/config/harpoon.lua

@@ -0,0 +1,106 @@
+local M = {}
+
+function M.setup()
+  local harpoon = require 'harpoon'
+  harpoon:setup {
+    settings = {
+      save_on_toggle = false,
+      sync_on_ui_close = false,
+      key = function()
+        return vim.loop.cwd()
+      end,
+    },
+  }
+
+  -- Add current file to list
+  vim.keymap.set('n', '<leader>ma', function()
+    harpoon:list():add()
+    vim.notify('Added to Harpoon', vim.log.levels.INFO)
+  end, { desc = '[M]ark [A]dd file (Harpoon)' })
+
+  -- Toggle quick menu
+  vim.keymap.set('n', '<C-e>', function()
+    harpoon.ui:toggle_quick_menu(harpoon:list())
+  end, { desc = 'Toggle Harpoon menu' })
+
+  -- Quick navigation to files 1-4 using leader+m prefix
+  vim.keymap.set('n', '<leader>m1', function()
+    harpoon:list():select(1)
+  end, { desc = 'Jump to mark 1' })
+
+  vim.keymap.set('n', '<leader>m2', function()
+    harpoon:list():select(2)
+  end, { desc = 'Jump to mark 2' })
+
+  vim.keymap.set('n', '<leader>m3', function()
+    harpoon:list():select(3)
+  end, { desc = 'Jump to mark 3' })
+
+  vim.keymap.set('n', '<leader>m4', function()
+    harpoon:list():select(4)
+  end, { desc = 'Jump to mark 4' })
+
+  -- Alternative quick access with Alt/Option key (doesn't conflict)
+  vim.keymap.set('n', '<M-1>', function()
+    harpoon:list():select(1)
+  end, { desc = 'Harpoon file 1' })
+
+  vim.keymap.set('n', '<M-2>', function()
+    harpoon:list():select(2)
+  end, { desc = 'Harpoon file 2' })
+
+  vim.keymap.set('n', '<M-3>', function()
+    harpoon:list():select(3)
+  end, { desc = 'Harpoon file 3' })
+
+  vim.keymap.set('n', '<M-4>', function()
+    harpoon:list():select(4)
+  end, { desc = 'Harpoon file 4' })
+
+  -- Navigate between harpoon files
+  vim.keymap.set('n', '[m', function()
+    harpoon:list():prev()
+  end, { desc = 'Previous marked file' })
+
+  vim.keymap.set('n', ']m', function()
+    harpoon:list():next()
+  end, { desc = 'Next marked file' })
+
+  -- Show harpoon files in Telescope
+  local conf = require('telescope.config').values
+  local function toggle_telescope(harpoon_files)
+    local file_paths = {}
+    for _, item in ipairs(harpoon_files.items) do
+      table.insert(file_paths, item.value)
+    end
+
+    require('telescope.pickers')
+      .new({}, {
+        prompt_title = 'Harpoon',
+        finder = require('telescope.finders').new_table {
+          results = file_paths,
+        },
+        previewer = conf.file_previewer {},
+        sorter = conf.generic_sorter {},
+      })
+      :find()
+  end
+
+  vim.keymap.set('n', '<leader>mm', function()
+    toggle_telescope(harpoon:list())
+  end, { desc = '[M]arked files in Telescope' })
+
+  -- Clear all marks
+  vim.keymap.set('n', '<leader>mc', function()
+    harpoon:list():clear()
+    vim.notify('Cleared all Harpoon marks', vim.log.levels.INFO)
+  end, { desc = '[M]arks [C]lear all' })
+
+  -- Remove current file from harpoon
+  vim.keymap.set('n', '<leader>mr', function()
+    harpoon:list():remove()
+    vim.notify('Removed from Harpoon', vim.log.levels.INFO)
+  end, { desc = '[M]ark [R]emove current file' })
+end
+
+return M