Consume typed terminal engine errors

[pierremtb]

Summary

• consume the typed modeling connection_error websocket response
• map every currently emitted connection error code to the app-level error taxonomy and honor the API's retryable field
• remove the base PR's legacy backend-message classifier and legacy auth-error handling
• include the cloud project ID in typed backend-disconnect telemetry when it is available
• preserve regression coverage proving the common pre-header auth_token_missing response is non-terminal

Stack

• minimal backend-disconnect behavior: Stop reconnecting after backend disconnects #13302
• API emission and OpenAPI schema: KittyCAD/api#4472
• shared protocol types: Add typed modeling connection errors modeling-api#1340

This PR intentionally targets pierremtb/issue-13161-terminal-engine-errors, not main, and assumes the API change deploys first. The latest published @kittycad/lib (4.4.9) still lacks ModelingWebSocketResponse, ConnectionErrorWebSocketResponse, and ModelingConnectionErrorCode, so the local compatibility type remains until the schema is released; it can then become a type-only import.

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Project	Deployment	Actions	Updated
modeling-app	Ready	Preview	Sep 8, 2026 5:35pm UTC