feat: auto-register repositories via PSDependOptions.Repositories (#50)

[HeyItsGilbert]

Summary

Closes #50. PSDepend DependencyFiles that reference a private repository currently break on any machine where that repository isn't pre-registered. This PR lets the DependencyFile declare the URL once, and PSDepend handles registration automatically.

• Adds PSDependOptions.Repositories — a file-level hashtable mapping repository names to source URLs
• PSGalleryModule, PSResourceGet, and Package DependencyScripts auto-register an unregistered repository if its name appears in the registry (persistent, Trusted, using the Dependency's Credential if present)
• Warns (does not error) if a repository is already registered at a different URL
• Test action is unchanged — never registers anything

Usage

@{
    PSDependOptions = @{
        Target = 'CurrentUser'
        Repositories = @{
            # PSGalleryModule / PSResourceGet: bare string URL
            MyPrivateGallery = 'https://my.feed/nuget'
            # Package: hashtable with Url + ProviderName
            MyNugetFeed      = @{ Url = 'https://my.feed/v3'; ProviderName = 'nuget' }
        }
    }
    'MyModule' = @{
        DependencyType = 'PSGalleryModule'
        Parameters     = @{ Repository = 'MyPrivateGallery' }
    }
}

Design decisions

An ADR is included at docs/adr/0001-repository-registry-in-psdependoptions.md capturing the key trade-offs: why file-level declaration over per-Dependency URL, and why persistent over ephemeral registration.

Seeking feedback on

• Naming: Repositories in PSDependOptions — does this collide with anything in your setups?
• The Package type requires a hashtable @{Url=…; ProviderName=…} while the module types take a bare string — is this acceptable or should the shape be unified?
• Should Test return $false when the repository itself isn't registered, even if the module is installed? (Current implementation: no.)

Test plan

• All existing Pester tests pass (verified locally: 241 passed, 2 skipped, 0 failed)
• Manual test: PSGalleryModule against an unregistered private repo name with a matching Repositories entry
• Manual test: URL mismatch warning fires when repo is already registered at a different URL
• Manual test: PSResourceGet and Package equivalents

🤖 Generated with Claude Code

[github-actions]

Test Results

    3 files     66 suites   1m 22s ⏱️
  979 tests   925 ✅ 54 💤 0 ❌
1 311 runs  1 247 ✅ 64 💤 0 ❌

Results for commit 79df1bf.