Paste body lost when Enter arrives during managed-account policy startup #5449

Bug

Copilot CLI 1.0.109 loses a multiline paste when Enter arrives during startup while managed-account policy is still loading. The composer retains [Paste #1 - N lines], but the pasted body is discarded; a later submission produces an empty user message.

Reproduction

1. Launch the interactive Copilot CLI with a policy load taking longer than about 0.6 seconds.
2. Immediately paste a multiline prompt and press Enter about 0.6 seconds after launch.
3. Observe Managed account policy is still loading. Please wait a moment and try again. Press Enter after the policy resolves and inspect the submitted message.

Actual

The placeholder remains in the composer, but the submitted user message has empty content. In observed failures the policy warning appeared at +0.60-0.66 seconds; policy resolved at +1.09-1.17 seconds. The same 95-line text failed once and worked on retry, so length was not the cause.

Expected

Queue submission until policy readiness, or retain the pasted body when submission is rejected so it can be retried without losing text.

Related: #218 reports a different form of input loss.