feat(host-cli): notify removed devices

[pgherveou]

Summary

• send one SSO Disconnected message to the selected pairing host before deleting its local pairing
• keep peer-initiated disconnect cleanup local so it never echoes another disconnect
• preserve the saved pairing, responder, and renewal target when notification submission fails
• add focused runtime and CLI regression coverage plus a reusable two-host CLI harness

This matches the removal order on polkadot-ios-community/develop: RemoveDeviceInteractor awaits disconnectHost, and SSOTruAPICoordinator sends its disconnect request before removing the host. The iOS contact-device broadcast has no CLI equivalent and is not included here.

Verification

• cargo +nightly fmt --check
• cargo build --workspace --all-targets
• cargo test --workspace --all-targets
• cargo test -p truapi-server disconnect_paired_host_ -- --nocapture --test-threads=1
• bash -n rust/crates/truapi-host-cli/e2e/device-removal-disconnect.sh
• shellcheck rust/crates/truapi-host-cli/e2e/device-removal-disconnect.sh
• Prettier check and Bun compilation for device-removal-disconnect.ts
• git diff --check

All automated checks passed without warnings. The workspace test run included 771 server tests, 208 CLI unit tests, and 14 CLI process tests. Existing network-dependent tests remained ignored.

Live two-host verification

The new harness was exercised with separate pairing-host and interactive signing-host CLI processes on both paseo-next-v2 and previewnet. Signer onboarding completed, but the existing pairing prerequisite failed before the changed removal path: both Statement Store allowance extrinsics were rejected with Invalid Transaction (1010), so no pairing session was persisted and a remote Disconnected could not be observed. Direct People-chain timestamp reads matched the local clock, ruling out local period skew.

The harness remains in this PR so the full Connected to Disconnected flow, pairing-host auth-storage cleanup, and empty signing-host device list can be rerun when allowance allocation is operational.