add console spooling

[korewaChino]

adds an ability to view the last 1MB of console history, combined with the ability to send data to the serial console, so consoles can be interactive

[cubic-dev-ai]

We've triggered an ultrareview automatically — This PR introduces concurrent console spooling with a bounded ring buffer and Unix socket attach, adds a new API endpoint, and modifies console path resolution—high-risk for data races, console reliability, and cross-VM behavior.. I'll post findings when complete.

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