feat(plugins): add fff fuzzy finder and supermaven LeetCode toggle plugins

lua/plugins/fff.lua

@@ -0,0 +1,18 @@
+--- fff.nvim: rust-backed fuzzy file finder and live grep with frecency
+--- Backs the <C-f> file/grep bindings in plugins/astrocore.lua. Honours
+--- .gitignore plus per-repo .ignore files; the config.ignore_patterns
+--- snacks filter does not apply here (snacks remains for non-file sources:
+--- diagnostics, lines, LSP symbols, recent, projects, templates).
+--- @module plugins.fff
+
+return {
+  "dmtrKovalenko/fff",
+  build = function()
+    -- downloads a prebuilt binary or falls back to cargo build
+    require("fff.download").download_or_build_binary()
+  end,
+  lazy = false, -- the plugin lazy-initialises itself
+  opts = {
+    lazy_sync = true,
+  },
+}