Bring the guide back in line with the app before 1.0 - #297

Closes #298.

## Why

#297 fixed the guide's text for everything that shipped since
`v1.0.0-beta.1`, but three pictures still showed the pre-1.0 app: no
build-watch button, the old four-click checklist, a Trac panel with no
ticket facts.

Retaking them turned out to be blocked on the harness, not on the
camera. Each of these states is one no seeded site can reach:

- the **wp-admin** link renders only while a dev server is serving, and
fixture sites are empty directories;
- the **self-setup chain** arms on the clone-finished edge, so a site
that was already in the registry when the app started never runs it;
- a **ticket's own facts** come from a live visit to its Trac page and
are held in memory, never written to the site's metadata.

## What changes

`shots.cjs` moves `setup-wizard`, `site-view` and `trac-ticket-panel` to
the live tier, next to `dev-server-running`, ordered so one site walks
all four in sequence. The header comment records why each cannot be a
fixture, so the next person does not move them back.

`capture.cjs` grows `--user-data=<dir>` for the live tier, so a capture
session runs against a documentation profile instead of the maintainer's
own registry. The existing guard stays — it exists so a stray *exported*
`TOOLKIT_USER_DATA_DIR` cannot silently redirect a run, and a path typed
on the command line is a decision, not a leftover. The flag is refused
on the fixture tier, which builds its own throwaway profile.

The four images come from one real site the app created at
`/private/tmp/wpct-docs/my-first-patch` — a real clone, install, build,
dev server and Trac read. No username in any pixel.

`dev-server-running.png` is new, and answers the half of #298 a single
picture could not: `site-view.png` stays in the stopped state, so the
guide's "shows a **Start dev server** button" prose still matches, and
the wp-admin link gets its own shot in *Running the site*.

Re-running the fixture tier also refreshed `site-menu`,
`stale-site-notice` and `debug-log`: same pre-1.0 button row, same fix.

Alt text follows the new pictures in `getting-started.md`,
`running-the-site.md`, `setup-wizard.md` and `trac-tickets.md`, and the
`docs.yml` comment now says four shots need a maintainer.

## Review

The ticket in the panel is
[#65856](https://core.trac.wordpress.org/ticket/65856), which has no
keywords set, so that row of the facts card is absent — the card renders
what the ticket has.

The images were driven programmatically rather than clicked by hand,
using the same launch config the harness uses (1200×800, DPR 1) with the
folder picker answered through `dialog.showOpenDialog`. The live tier
itself is unchanged as the documented, maintainer-at-the-keyboard path.

## Testing

- `npm run lint`, `npm test` (937 pass), `cd docs && npm run build` —
green.
- `npm run shots` (fixture tier) still captures its eight shots;
`--only=site-view` on the fixture tier now fails loudly with the
known-slug list, and `--user-data` on the fixture tier is refused.
- Every image is 1200×800 at DPR 1, and no path in any picture contains
a username.

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Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>