gateway: serve the dashboard at wild-pc.<domain>, 404 unrouted subdomains

The dashboard's deployment kept the pre-rename name `wildpc`, so it was
published at wildpc.<domain> while everything else had moved to Wild PC
naming. Rename the deployment and its program to `wild-pc` (the subdomain
is the deployment name) and follow the `_DASHBOARD` constant in both the
Caddyfile generator and doctor — that constant also drives the `:9000`
redirect and doctor's `wildpc program build` hint, which is why the
program is renamed alongside the deployment.

Browsing the old name exposed a second problem: in acme mode every route
lives inside one `*.<domain>` wildcard site, so an unrouted host still
matches the site and completes its TLS handshake. Caddy then ran off the
end of the block and returned a bare 200 with an empty body — a typo'd or
renamed subdomain looked *up* in a browser while rendering nothing. Each
wildcard site now ends with an unmatched `handle` that responds 404.

The API subdomain is untouched: the dashboard derives its API origin by
stripping the first label, so wild-pc.<domain> still resolves to
wildpc-api.<domain>, and the WebSocket origin gate matches on
gateway.domain rather than a hostname.

Also seed the bootstrap dashboard deployment with the `requires:
wildpc-api` block the live deployment already carried, so a fresh install
declares the dependency.

bootstrap/programs/wild-pc.yaml

@@ -0,0 +1,6 @@
+description: Wild PC web app
+source: repo:app
+stack: react-vite
+build:
+  outputs:
+  - dist/