Implement Package Provider System

[OMouta]

Introduce a package provider abstraction in Luumen to decouple package management from Wally and allow alternative implementations (e.g. future Luumen package client).

This is a foundational step to support multiple package backends while keeping a unified CLI (luu add, luu install, etc.).

Goals

• Standardize how Luumen interacts with package management
• Keep Wally as the default provider
• Allow future providers without changing CLI UX

1. Define provider interface

Create a simple interface:

type PackageProvider interface {
    Add(pkg string, opts AddOptions) error
    Install(opts InstallOptions) error
    Remove(pkg string) error
    Update(pkg string) error
}

2. Implement Wally provider

Create a WallyProvider that:

• Updates wally.toml
• Calls wally install when needed
• Handles add/remove/update flows using current Luumen logic

3. Provider selection

Add basic provider selection logic:

• Default to Wally
• Allow future config support

Example:

[packages]
provider = "wally"

4. Route CLI through provider

Update:

luu add
luu install
luu remove (if exists)
luu update (if exists)

So they call the provider instead of directly calling Wally logic.