Self-corrections are never applied when the recogniser writes the trigger as its own sentence ("Tuesday. Scratch that. Wednesday")

## What happens

Whisper often writes a paused trigger phrase as a separate sentence. `Restatement` refuses to reach across a sentence end (`endsSentence`, `Sources/UttrflowCore/Cleaning/Restatement.swift:46-50, 66, 70-72`), which is right for real sentences (#199) but means these corrections are never applied.

From `uttrflow-dev bench` on main, synthetic clips (shipping and rules gave the same text unless noted):

| Clip (said) | Recogniser | Inserted |
|---|---|---|
| "Meet me on Tuesday, scratch that, Wednesday at noon." US voice | `Meet me on Tuesday. Scratch that. Wednesday at noon.` | unchanged |
| same, Indian English voice | `Meet me on Tuesday. Scratch that. Wednesday at noon.` | unchanged |
| "The total is forty dollars, no wait, fifty dollars." US voice | `The total is $40. No wait. $50.` | unchanged |
| same, Indian English voice | `The total is $40. No wait. $50.` | unchanged |
| same, UK voice | `The total is $40, no wait, $50.` | shipping `The total is $50.`, rules `The total is $$50.` (#550) |

So 4 of the 6 clips kept both halves because of the recogniser's full stops alone. (The "Tuesday … Wednesday" form also needs a shape match the rule does not make; that is by design in `Docs/cleanup.md` and not this issue.)

Reproduce the rules half without audio:

```
.build/release/uttrflow-dev clean --engine rules 'The total is $40. No wait. $50.'
```

## Why it matters

A trigger said with a pause is the most deliberate kind of self-correction, and the one a person is most sure they made.

## Acceptance criteria

- A sentence consisting only of a trigger phrase ("No wait.", "Scratch that.", "Sorry.", "I mean.") is read through as not ending a sentence, the way `PieceJoiner` already reads through a full stop at a piece seam (`Docs/cleanup.md`, self-correction row).
- A real sentence that happens to start with "No." ("No. We shipped it.") is not affected.
- Tests in `RestatementTests` / `SelfCorrectionPassTests`, and a corpus case with the trigger as its own sentence.

Read Restatement.swift at lines 46-50, 66, and 70-72, then compare its sentence-boundary handling with PieceJoiner and Docs/cleanup.md. Reproduce the rules case with `.build/release/uttrflow-dev clean --engine rules 'The total is $40. No wait. $50.'`. Update the behavior and add coverage in RestatementTests, SelfCorrectionPassTests, and the corpus case while preserving real sentences beginning with “No.”.

Written by the indexing model from the issue text.