feat(ui): modernize nvim with fzf-lua, snacks dashboard, and p10k-style statusline

- Replace Snacks picker with fzf-lua for LSP navigation (gd, gr, gi, gt)
- Add fzf-lua plugin with LSP-optimized settings
- Fix Mason inconsistencies (add eslint, gopls to ensure_installed)
- Replace alpha-nvim with Snacks dashboard (shared config)
- Create dashboard_config.lua for DRY dashboard settings
- Modernize lualine with p10k-rainbow style and solid backgrounds
- Enhance bufferline with LSP diagnostics and modern styling
- Update noice with centered cmdline/search and modern icons
- Add global rounded borders for floating windows
- Improve indent-blankline with scope highlighting
- Add return-to-dashboard on last buffer close
- Create performance_monitor module

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lua/cargdev/plugins/fzf-lua.lua

@@ -0,0 +1,39 @@
+return {
+  "ibhagwan/fzf-lua",
+  dependencies = { "nvim-tree/nvim-web-devicons" },
+  config = function()
+    local fzf = require("fzf-lua")
+    fzf.setup({
+      "default",
+      winopts = {
+        height = 0.85,
+        width = 0.80,
+        row = 0.35,
+        col = 0.50,
+        border = "rounded",
+        preview = {
+          layout = "flex",
+          flip_columns = 120,
+          scrollbar = "float",
+        },
+      },
+      keymap = {
+        builtin = {
+          ["<C-d>"] = "preview-page-down",
+          ["<C-u>"] = "preview-page-up",
+        },
+        fzf = {
+          ["ctrl-q"] = "select-all+accept",
+        },
+      },
+      lsp = {
+        async_or_timeout = 5000,
+        jump_to_single_result = true,
+        ignore_current_line = true,
+      },
+      diagnostics = {
+        severity_limit = vim.diagnostic.severity.HINT,
+      },
+    })
+  end,
+}