Add error toast (red background, 3× duration) for copy command failures

[Copilot]

Copy failures (e.g. xclip not installed) were visually indistinguishable from successes — both used the same green toast. Error conditions now render a distinct red toast that stays visible 3× longer.

Changes

• ToastComponent — adds showError(message) method; extracts shared display logic into _showWithOptions() which handles per-call background override and restoration after hide
• controller.ts — adds showErrorToast() alongside showToast(); copySelectedId() now routes all failure paths through showErrorToast() instead of showToast()
• test-utils.ts — mock toast and toastComponent expose showError() and lastIsError() for test assertions
• copy-id.test.ts — asserts lastIsError() === false on success and === true when a failure message is produced

// Success: green toast, 1200 ms
if (res.success) showToast('ID copied');
// Failure: red toast, 3600 ms
else showErrorToast(res.error ? `Copy failed: ${res.error}` : 'Copy failed');

Original prompt

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This section details on the original issue you should resolve

<issue_title>Error toasts</issue_title>
<issue_description>

Add an error toast that can be used when the system encounters an error. This should be like the current toasts only it should have a red background and should be visible for 3x as long. The first place this would be used would be for the copy command (C) in the TUI. If xclip is not installed this currently issues a toast that is an error, but it is indistinguishable to a success toast.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Clear GitHub sync mappings #400

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