Reconcile callers with actual function signatures after merging IO
migration branches. Some functions gained io.Medium params (repos.*),
others kept their original signatures (release.*, cache.*, container.*).
- Add io.Local to repos.LoadRegistry/FindRegistry/ScanDirectory callers
- Remove extra io.Local from release.ConfigExists/LoadConfig/WriteConfig callers
- Fix cache.New call (remove nil Medium arg)
- Add missing IsCPPProject to build discovery
- Add missing fields to mcp.Service struct (subsystems, logger, etc.)
- Add DefaultTCPAddr constant to mcp transport
- Fix node.go interface check (coreio.Medium, not coreio.Node)
- Fix container.linuxkit LoadState/EnsureLogsDir arg counts
- Fix vm templates to use package-level functions
- Remove unused Medium field from DaemonOptions
Co-Authored-By: Virgil <virgil@lethean.io>