Deleting a dictation leaves its clipboard copy behind when a correction in it was undone first

## What happens

A finished dictation is saved twice: as a history record, and as a clipboard clip holding `outcome.text` (`Sources/Uttrflow/AppDelegate.swift:1164`, `recordAsClip(outcome.text)`).

Deleting the dictation is meant to remove both ("Both files, or the words are still one shortcut away in the panel", `AppDelegate.swift:1561-1570`). It looks up the record's *current* text, then deletes clips whose `origin == .uttrflow && text == spoken` (`forgetClips(saying:)`, `:1048-1058`).

Undoing a correction rewrites the record's text (`Sources/UttrflowHistory/CorrectionUndo.swift:16`, `undone.text = restoring(...)`), but not the clip. Once a correction has been undone, the record text and the clip text differ, the match fails, and the original transcript stays in `clipboard.v1.json` and in the panel until the clipboard's own retention removes it. The same happens if the clip text was edited in the panel (`ClipboardStore.setText`, `Sources/UttrflowClipboard/ClipboardStore.swift:154-160`), and forever if the clip was pinned.

## Why it matters

Deleting a dictation is how someone removes words they should not have kept. The words stay one ⇧⌘V away, and nothing says so.

## How to reproduce

1. Dictate a sentence where a dictionary correction fires.
2. On the Dictation page, undo that correction.
3. Delete the dictation.
4. Open the clipboard panel: the original sentence is still there.

## Acceptance criteria

- The clip made from a dictation carries the dictation's id (or the history record carries the clip's id), and deleting the dictation deletes by id rather than by text.
- A test covers delete-after-undo and delete-after-panel-edit.

Start by tracing deletion in Sources/Uttrflow/AppDelegate.swift:1048-1058 and 1561-1570, then compare it with correction undo in Sources/UttrflowHistory/CorrectionUndo.swift:16 and edits in Sources/UttrflowClipboard/ClipboardStore.swift:154-160. Reproduce delete-after-undo and delete-after-panel-edit, then add tests showing that the associated clip is removed by identity even when its text differs or it is pinned.

Written by the indexing model from the issue text.