feat(connection): Add extended address parser (gt-f9x.10)
Implement address parsing for cross-machine operations:
Format: [machine:]rig[/polecat]
Examples:
- gastown/rictus -> local, gastown rig, rictus polecat
- vm:gastown/rictus -> vm machine, gastown rig, rictus
- gastown/ -> broadcast to gastown rig
Address struct with:
- ParseAddress() parser with validation
- String() canonical form
- IsLocal(), IsBroadcast() predicates
- Equal() comparison (normalizes local machine)
- Validate() against MachineRegistry
- RigPath() for rig/polecat without machine prefix
Includes comprehensive test coverage.
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>