Only invoke alias completion when the complete shell word is an alias name. Completion otherwise treats assignment values and quoted text as standalone alias names, corrupting inputs such as DEBUG=1.
Add a real ZLE regression test covering the reported assignments, quotes, escaped aliases, filtering, and existing expansion behavior.
Assisted-by: OpenAI Codex
Also:
- Changes `globes` (which doesn't exist) to `glob expressions`.
- Delete the `trigger autocompletion to your current aliases` use case, since that's not
really implemented.
