Handle invalid BridgeManager interface names safely

[fallintoplace]

Summary

• add a throwing BridgeManager.make(...) path for eager interface-name validation
• stop using precondition for bridge and egress interface validation so invalid input comes back as .invalidArgument
• switch the Linux CLI bridge call sites to the throwing path and add Linux-only coverage for invalid names

Why

BridgeManager.init currently treats invalid interface names as a programming error and traps the process. That is rough for CLI and API callers because bad user input turns into a crash instead of a normal error.

This change keeps the existing initializer source-compatible, validates before create() and delete() touch host state, and gives the CLI a throwing construction path so invalid names are reported cleanly.

Validation

• git diff --check
• local Linux execution was not available on this macOS machine, so the new Linux-only tests are left for CI