Add spawn_supervised(name, location, future) to utils.rs that wraps
futures in AssertUnwindSafe + catch_unwind, logs panics via tracing::error!,
and writes crash dumps to ~/.deepseek/crashes/.
Add process-level panic hook to main.rs that writes crash dumps before
the default hook fires.
Convert persistence_actor::spawn_persistence_actor as the first
spawn_supervised caller to prove the wiring. Remaining 34 tokio::spawn
sites marked as follow-up for a focused PR.
Also fix save_mcp_config in main.rs to use write_atomic (missed in #355).
Hunter Bown
a8be33b35b