chore(quality): resolve SonarQube code smells across website

Clears the 124 CODE_SMELL findings from the SonarQube scan (server, client,
and bot). All changes are behaviour-preserving refactors — no route, protocol,
schema, or config changes — verified against the full server (381) and client
(43) test suites plus a clean client build.

By rule:
- S3776 (20, cognitive complexity): extract helpers/handlers so each function
  drops under the threshold — shard model upsert builders, page/wiki update,
  block validation, notification stream mapping (dispatch table), SSO mobile
  login, shard ingest deps, uo-link socket backfill/connect, the bot slash-
  command dispatchers + discord manager, and the Shard/UserDetail/HeroEditor/
  CharacterStats React components.
- S4624 (34, nested template literals): pull inner templates into locals /
  a withQs() helper; rewrite shardEvents.describe() as a formatter table.
- S3358 (35, nested ternaries): lift to if/else vars, lookup maps, small
  components, or guarded JSX expressions.
- S6479 (12, array-index React keys): key by stable content instead of index
  (two in-editor lists left as-is; index matches their by-index edit model).
- S6353 (6): [0-9]/[^0-9] -> \d/\D.  S125 (5): reword state-shape comments that
  parsed as code.  S3800/S3782 (botScore): JSDoc-type PATH_WEIGHTS tuples.
- S6481 (2): memoize Auth/Site context values (and SiteContext brand).
- S4144: dedupe HeroEditor upload handler into useImageUpload().
- S1126 (2), S6035, S5869 (redundant A-Z under /i), S5843 (town-name regex ->
  prefix list): assorted one-liners.

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

client/src/routes/player/PlayerRegister.jsx

@@ -75,15 +75,17 @@ export default function PlayerRegister() {
         </p>
       }
     >
-      {avail === null ? (
+      {avail === null && (
         <div style={{ display: 'grid', placeItems: 'center', padding: 20 }}>
           <span className="spin" />
         </div>
-      ) : closed ? (
+      )}
+      {avail !== null && closed && (
         <p className="sans" style={{ margin: 0, color: 'var(--muted)', fontSize: '0.9rem', textAlign: 'center', lineHeight: 1.6 }}>
           Self-registration is currently closed. Please check back later.
         </p>
-      ) : (
+      )}
+      {avail !== null && !closed && (
         <>
           {avail.password && (
             <form onSubmit={onSubmit}>