Hide cloud follow-up input during setup commands

[zachbai]

Description

• Adds a tech spec for APP-4460.
• Hides the Cloud Mode follow-up input while setup-v2 setup commands are actively running for the current setup-command group.
• Adds a regression test for the input visibility transition after the setup-command group finishes.

Linked Issue

https://linear.app/warpdotdev/issue/APP-4460/input-should-be-hidden-when-running-setup-commands-in-follow-up

• The linked issue is labeled ready-to-spec or ready-to-implement.
• Where appropriate, screenshots or a short video of the implementation are included below (especially for user-visible or UI changes).

Testing

• cargo fmt --manifest-path /workspace/warp/Cargo.toml -p warp --check

• CARGO_BUILD_JOBS=1 cargo nextest run --manifest-path /workspace/warp/Cargo.toml -p warp -E 'test(cloud_mode_setup_v2_hides_input_while_followup_setup_commands_run)'

• CARGO_BUILD_JOBS=1 cargo clippy --manifest-path /workspace/warp/Cargo.toml -p warp --tests -- -D warnings

• I have manually tested my changes locally with ./script/run

Agent Mode

• Warp Agent Mode - This PR was created via Warp's AI Agent Mode

Co-Authored-By: Oz oz-agent@warp.dev

Conversation: https://staging.warp.dev/conversation/7e2c1637-d21b-43ac-b31f-a59186713a2c
Run: https://oz.staging.warp.dev/runs/019e1ec1-58ce-70b3-8f05-7c9810f14ada

This PR was generated with Oz.