Add winget package ecosystem support

[AgentGoose32]

Summary

• add a winget ecosystem adapter backed by the microsoft/winget-pkgs manifest repository
• maps package names from manifest paths and reads version, locale, and installer manifests
• maps package metadata, versions, registry/documentation URLs, install commands, and status checks
• seeds winget-pkgs as the default winget registry
• adds model coverage for package discovery, metadata, versions, URLs, and install commands

Refs #658

Validation

• ruby -c app/models/ecosystem/winget.rb
• ruby -c db/seeds.rb
• ruby -c test/models/ecosystem/winget_test.rb
• git diff --check

Full Rails test execution is blocked locally because this repo lockfile requires Bundler 4.0.10 while the system Ruby/Bundler cannot satisfy it.