Promote collections to a top-level command

[simonw]

Currently the CLI tools for managing collections are tucked away in llm embed-db:

llm embed-db --help
Usage: llm embed-db [OPTIONS] COMMAND [ARGS]...

  Manage the embeddings database

Options:
  --help  Show this message and exit.

Commands:
  collections        Output the path to the embeddings database
  delete-collection  Delete the specified collection
  path               Output the path to the embeddings database

I think collections deserve to be a top-level concern in the CLI tool, so you can do this:

# View collections
llm collections

# Delete a collection
llm collections delete my-collection

# View items in a collection
llm collections show my-collection

Not completely happy with that last command. Some options:

• llm collections my-collection - uses up the namespace that I want to use for llm collections delete and suchlike
• llm collections list my-collection - confusing since llm collections is presumably a default alias of llm collections list same as how llm aliases list and llm templates list and llm models list work.

[simonw]

I could drop llm embed-db entirely if I move this command to collections instead:

llm collections path

[simonw]

I'm going with llm collections show xxx for consistency with llm templates show xxx.