fix(client): back off reconnects when the stream never connects - #47204

Issue for this PR

Fixes #47062

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

The event-stream client retried on a fixed one-second delay regardless of why the stream died, so an unauthenticated browser session re-triggered the Basic auth prompt every second while the shell sat there unauthenticated. Streams that never connected successfully now scale the retry delay with the attempt count up to 30 seconds, which gives the browser prompt time to be answered; streams that connected and later dropped reset the attempt counter and keep the existing one-second retry.

The failure reason is intentionally not inspected — a declared 401 with an empty body surfaces client-side as an indistinguishable ClientError("UnsupportedContentType"), and the never-connected case is the one that needs the guard regardless of cause.

How did you verify your code works?

• New test/solid-connection.test.ts: a 401-empty-response API under a real clock — reconnect attempts stay monotonically increasing across 400ms and the inter-attempt gaps grow (no backoff would produce ~20 attempts, backoff produces ~7)
• reconnectBackoffDelay unit cases for scaling, the 30s cap, and the attempt-0 floor
• bun typecheck + full packages/client suite (152 passing)

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR