test(client): check what the chunk registers, and fix two defects in the checks

Three things, all about checks that had never met a real chunk.

`checkExternals.js` rejected slice 3's build outright, naming a fragment of
minified JSX as an imported specifier: a button reading "Approve and import"
puts the token immediately before a quote, and no regexp can tell that from a
statement. Same wall the server's `checkImports.js` hit, answered the same way —
a character walk. A mask rather than a rewrite, because a real import has its
keyword outside a string and its specifier inside one.

Writing the test for that false positive found the false NEGATIVE underneath
it: the pattern required whitespace after `import`, so it could not see
`import{useState}from"react"` — the one shape a minified build actually emits,
and the most likely way for a missed alias to reach production. It has never
been able to see it.

`registration.test.js` is new: stand up a fake `window.__rg` with a recording
registry and the real React, import the BUILT chunk, and read back what it
asked for. No DOM, because nothing renders. It holds the agreement that rots
quietly — every nav row points at a route this module actually registered —
rather than restating both lists.

CI now builds before it tests, because both of those read `dist/entry.js` and
skip without it. Run the other way round they are green and asking nothing.

Co-Authored-By: Claude <noreply@anthropic.com>

module.json

@@ -1,8 +1,8 @@
 {
   "id": "uo",
   "name": "Ultima Online",
-  "version": "0.2.0",
-  "coreApi": "^1.1.0",
+  "version": "0.3.0",
+  "coreApi": "^1.3.0",
   "server": "server/index.js",
   "client": { "entry": "client/dist/entry.js" },
   "schema": "server/db/schema.sql",