Replace the maintainer's name in test fixtures with neutral values

## What

Eleven files carry the maintainer's first name as fixture data — `/Users//…` sample paths, a dictionary demo entry, and a recording-cohort id. They are harmless, but a fixture should be invented, not observed, and the repo's own `Scripts/pii_audit.sh` rule is "if you can see it from where you are sitting, that is the reason not to use it".

Files (from `git grep`):

- `Tests/UttrflowClipboardTests/PathShapeTests.swift`
- `Tests/UttrflowClipboardTests/SecretDetectionTests.swift`
- `Tests/UttrflowEvalTests/AccuracyBaselineTests.swift`
- `Sources/uttrflow-eval/RecordCorpus.swift` (help text example)
- `Docs/operator-runbook.md`
- `Design/_gen_app.py`, `Design/Main-Corrections.dc.html`, `Design/Main-Corrections-Dark.dc.html`

## Care points

- `PathShapeTests` asserts on path *shape*, so the replacement must keep the same segment count and punctuation.
- The dictionary demo (`" " → ""`) demonstrates a one-letter correction. Pick a replacement pair with the same property.
- The design `.dc.html` files are generated by `Design/_gen_app.py`; change the generator, then regenerate.

## How to check

`make verify` passes and `git grep -i` for the old strings returns nothing.