Fix: lazy keys break multi-key sequences (e.g. vib)

Problem

When a plugin is lazy-loaded by a key like i (mode x/o), pressing a multi-key sequence such as vib does not work on the first invocation. It behaves as if only vb was pressed.

Repro with mini.ai:

{
  "nvim-mini/mini.ai",
  keys = {
    { "a", mode = { "x", "o" } },
    { "i", mode = { "x", "o" } },
  },
  config = function() require("mini.ai").setup() end,
}

Full config example here

Place cursor inside { "a", "b", "c" }, press vib — selection fails.
It behaves as if only vb was pressed (visual mode, then move back a word).
It works on second try because plugin already loaded.

Cause

In lua/zpack/lazy_trigger/keys.lua the proxy re-feeds the lhs with:

vim.api.nvim_feedkeys(vim.keycode(lhs), 'm', false)

The 'm' flag appends to the typeahead. When pressing vib:

1. v enters visual
2. i fires the proxy; b is already queued in typeahead
3. proxy appends i → final order becomes b, i
4. b runs first (move back word) — observed behavior is vb

lazy.nvim solves this with the 'i' flag (insert at front) — see lazy/core/handler/keys.lua#L140.

Fix

One-character change: 'm' → 'i'.

Test

Added a brief regression test in tests/lazy_keys_test.lua.
Fails on old code, passes after the fix. All 333 → 334 tests pass.