Remote comms: Kernel incarnation detection

[sirtimid]

Problem: When a peer reconnects, we can't tell if it's the same kernel or a new incarnation. Promises from the previous incarnation should be rejected, but we currently treat all reconnections as the same kernel.

Expected Behavior:

• Detect when a reconnected peer is a new kernel incarnation (different from previous)
• Reject all promises from the previous incarnation when new incarnation detected
• Track incarnation identity (could be part of peer identity or handshake)
• Handle incarnation changes gracefully without breaking new connections

Implementation:

• Add incarnation tracking to connection/channel state
• Implement incarnation detection mechanism (peer identity comparison, handshake, or protocol-level)
• On incarnation change detection, find and reject promises from old incarnation (using Task #2 pattern)
• Update RemoteHandle or promise management to track incarnation
• Coordinate with RemoteManager for promise rejection
• Add tests for incarnation detection and promise rejection

Acceptance Criteria:

• Incarnation changes are detected
• Promises from previous incarnation are rejected on new incarnation
• New connections work normally after incarnation change
• Tests verify incarnation detection and promise cleanup

Dependencies: Remote comms: Promise rejection on give-up