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>

server/src/model/wiki/wiki.model.js

@@ -98,11 +98,10 @@ async function create({ slug, title, body, excerpt, categoryId, published, updat
   return getBySlug(slug)
 }
 
-// Partial update — only keys present in `input` are written.
-async function update(slug, input) {
-  const current = await wikiDb.findBySlug(slug)
-  if (!current) return null
-
+// Map the partial `input` to DB columns (only keys present are written), and
+// report the cleaned body for link rebuilding when the body changed. Split out of
+// update() so that stays a flat sequence of write steps.
+function mapUpdateFields(input, current) {
   const fields = { updated_by: input.updatedBy ?? null }
   let cleanForLinks = null
   if ('title' in input) fields.title = input.title
@@ -116,7 +115,15 @@ async function update(slug, input) {
     fields.published = input.published ? 1 : 0
     if (input.published && !current.published_at) fields.published_at = new Date()
   }
+  return { fields, cleanForLinks }
+}
 
+// Partial update — only keys present in `input` are written.
+async function update(slug, input) {
+  const current = await wikiDb.findBySlug(slug)
+  if (!current) return null
+
+  const { fields, cleanForLinks } = mapUpdateFields(input, current)
   await wikiDb.updateBySlug(slug, fields)
   if (Array.isArray(input.tags)) await syncTags(current.id, input.tags)
   if (cleanForLinks != null) await rebuildLinks(current.id, cleanForLinks)