fix: use `lodash.template` directly to compile template

[danielroe]

We are going to be removing support for compiling templates from disk using lodash.template in Nuxt v4. This is a PR to move lodash usage directly into the module to avoid breaking it on Nuxt 4.

It would also be possible to avoid using it entirely, which I would strongly recommend, either:

• using a custom function to handle the replacement, such as in https://github.com/nuxt-modules/color-mode/pull/240
• or moving the string interpolation logic directly into getContents