fix(rust): answer refusals in the field core reads, and show the name the game last saw

The two defects the phase 6 browser walk found and #6 described but did not
carry. They were written, walked and left uncommitted; `edge` still has the
shapes the walk condemned.

**Every refusal sentence was invisible.** Core's request primitive reads one
field — `(data && data.message) || res.statusText` — and this module has
answered `{ error: … }` since phase 1. It got away with it because every
failure until phase 6 landed in `ErrorState` on a page whose whole content was
missing, where a generic sentence is honest. A form is different: the sentence
IS the outcome, and the link page showed *Service Unavailable* for all four of
the refusals phase 6 exists to write. All 23 bodies now answer in `message` —
core's `Error` schema, which these routes' own `#swagger.responses` already
referenced, so the annotations stop being a claim the handlers contradict.

`test/errorShape.test.js` drives each outcome rather than grepping for the
field, and asserts the half that is easy to leave behind: a body carrying BOTH
fields renders correctly in a browser and keeps the wrong shape alive for the
next route that copies it.

**The player saw a stale name.** `/player/rust` showed the name recorded at
link time while the admin panel showed the one the game last saw — the same
person labelled two ways on one site, because a Rust name changes on a whim and
only the admin read joined `rust_players`. A LEFT JOIN, because an account can
be linked and never played on.

123 server tests, 39 client tests, `check:imports`, `check:bundle`,
`check:swagger`, `check:externals` — all green.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PMH6bw1jXMgbyF3ZWGEzSM

server/router/player/rust.controller.js

@@ -31,7 +31,7 @@ async function listServers(req, res) {
     res.json({ servers: await servers.listPublic() })
   } catch (err) {
     log.error('failed to read the server list', { error: err.message })
-    res.status(500).json({ error: 'Failed to read the server list' })
+    res.status(500).json({ message: 'Failed to read the server list' })
   }
 }
 
@@ -41,7 +41,7 @@ async function listLinks(req, res) {
     res.json({ links: await links.listForUser(req.user.id) })
   } catch (err) {
     log.error('failed to read a player’s links', { error: err.message })
-    res.status(500).json({ error: 'Failed to read your linked accounts' })
+    res.status(500).json({ message: 'Failed to read your linked accounts' })
   }
 }
 
@@ -79,34 +79,34 @@ async function confirmLink(req, res) {
         // signed in, the account named is one they may well own, and without the
         // name the advice ("sign in as that account, or ask staff") is unusable.
         return res.status(409).json({
-          error: result.username
+          message: result.username
             ? `That Steam account is already linked to ${result.username}. Run /unlink in game to release it.`
             : 'That Steam account is already linked to another website account. Run /unlink in game to release it.',
         })
 
       case 'unsure':
         return res.status(503).json({
-          error:
+          message:
             'One of the servers could not be reached, so that code could not be checked. ' +
             'Your code is still good — try again in a minute.',
         })
 
       case 'offline':
         return res.status(503).json({
-          error: 'The game servers are unreachable right now — try again in a minute.',
+          message: 'The game servers are unreachable right now — try again in a minute.',
         })
 
       case 'no-servers':
-        return res.status(503).json({ error: 'No Rust servers are configured on this site yet.' })
+        return res.status(503).json({ message: 'No Rust servers are configured on this site yet.' })
 
       default:
         return res.status(400).json({
-          error: 'That code is unknown or has expired. Type /link in game for a new one.',
+          message: 'That code is unknown or has expired. Type /link in game for a new one.',
         })
     }
   } catch (err) {
     log.error('failed to confirm a link code', { error: err.message })
-    return res.status(500).json({ error: 'Failed to confirm that code' })
+    return res.status(500).json({ message: 'Failed to confirm that code' })
   }
 }
 
@@ -123,14 +123,14 @@ async function removeLink(req, res) {
   try {
     const removed = await links.unlinkOwned(steamId, req.user.id)
 
-    if (!removed) return res.status(404).json({ error: 'That account is not linked to you' })
+    if (!removed) return res.status(404).json({ message: 'That account is not linked to you' })
 
     await core.activity.log({ req, action: 'rust.account.unlink', detail: { steamId } })
 
     return res.json({ unlinked: true })
   } catch (err) {
     log.error('failed to unlink', { error: err.message })
-    return res.status(500).json({ error: 'Failed to unlink that account' })
+    return res.status(500).json({ message: 'Failed to unlink that account' })
   }
 }