fix(review): 4 issues found in agent review of PR #535

BUG-1 (CRITICAL): messages.js line 522 — mismatched quote in
setComposerStatus('Reconnecting…') caused JS syntax error on the
reconnect path.

BUG-2 (HIGH): messages.js line 491 — broken template literal
'\\n\\n*{d.hint}*' restored to '\n\n*${d.hint}*'. Error hint
text was non-functional (missing $ prefix and escaped newlines).

BUG-3 (HIGH): messages.js — showApprovalCard(pending, pendingCount),
_approvalCurrentId, and approval_id in respondApproval() were removed,
regressing the simultaneous approval queue fix from PR #546. Restored
all three, including the '1 of N pending' counter and poll passthrough.

BUG-4 (LOW): api/streaming.py — MiniMax thinking delimiter regex
missing closing pipe: <|channel> -> <|channel|> in both
_strip_thinking_markup() and _looks_invalid_generated_title().

ALSO: test_issue487b.py docstring changed to raw string to fix
DeprecationWarning for invalid escape sequence '\s'.

static/messages.js

@@ -488,7 +488,7 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
           const isAuthMismatch=d.type==='auth_mismatch';
           const isNoResponse=d.type==='no_response';
           const label=isRateLimit?'Rate limit reached':isAuthMismatch?(typeof t==='function'?t('provider_mismatch_label'):'Provider mismatch'):isNoResponse?'No response received':'Error';
-          const hint=d.hint?`\\n\\n*{d.hint}*`:'';
+          const hint=d.hint?`\n\n*${d.hint}*`:'';
           S.messages.push({role:'assistant',content:`**${label}:** ${d.message}${hint}`});
         }catch(_){
           S.messages.push({role:'assistant',content:'**Error:** An error occurred. Check server logs.'});
@@ -519,7 +519,7 @@ function attachLiveStream(activeSid, streamId, uploaded=[], options={}){
       // Attempt one reconnect if the stream is still active server-side
       if(!_reconnectAttempted && streamId){
         _reconnectAttempted=true;
-        setComposerStatus('Reconnecting…");
+        setComposerStatus('Reconnecting…');
         setTimeout(async()=>{
           try{
             const st=await api(`/api/chat/stream/status?stream_id=${encodeURIComponent(streamId)}`);