Expose bounded MCP crash checkpoints

[bordumb]

Outcome

TypeScript and Python now expose an identical, inert observer port for deterministic MCP execution checkpoints. The port lets a host process schedule real process death at six bounded lifecycle boundaries without reproducing Auths semantics outside the SDK.

Checkpoints

• before verification
• after verification
• after durable reservation
• before provider transmission
• after provider transmission
• before receipt persistence

Events are immutable, carry an execution identity only after reservation, and are propagated through execute, resume, recover, delegation, and recoverable development composition. Invalid observers fail before resources are opened.

Validation

• TypeScript build and public API snapshot
• 9 focused TypeScript integration tests
• Rust formatting
• semantic freeze (57 entries, 39 public Rust packages)
• pre-rebase Python focused tests, strict typing, lint, and formatting; hermetic cross-platform validation delegated to CI