fix: i18n cleanup + readiness checklist effect cadence + ChordPicker shadow

- DictationReadinessChecklist was constructing downloadByModel as a fresh Map every render and listing it in the cleanup effect's deps. With the 1 s polling cadence and arbitrary parent rerenders the effect ran more often than it needed to. Memoised the Map on activeTasks; the effect now keys off the memo's identity.
- zh-CN persona tooltipActive/ariaLabelActive matched their inactive twins byte-for-byte ("以人物设定朗读"). The other locales differentiate the active state with a -ing / -中 suffix; zh-CN now reads "正以人物设定朗读" when active.
- personalityPlaceholder was a ~290-character paragraph that doubled as both the example text and the explanation, repeating most of what personalityHint already said. Trimmed to the example only and folded the explanation + leave-blank consequence into the hint, across all four locales.
- Refinement model size keys were size06 / size17 / size4. Renamed the 4B variant to size40 so the decimal padding is consistent.
- ChordPicker's open-effect bound a window.setTimeout id to a local `t`, shadowing the i18n `t` from useTranslation. Renamed to timeoutId.

app/src/components/CapturesTab/DictationReadinessChecklist.tsx

@@ -9,7 +9,7 @@ import {
   Keyboard,
   Loader2,
 } from 'lucide-react';
-import { useEffect, useRef } from 'react';
+import { useEffect, useMemo, useRef } from 'react';
 import { useTranslation } from 'react-i18next';
 import { Button } from '@/components/ui/button';
 import { useToast } from '@/components/ui/use-toast';
@@ -103,10 +103,16 @@ export function DictationReadinessChecklist({
     },
   });
 
-  const downloadByModel = new Map<string, ActiveDownloadTask>();
-  for (const dl of activeTasks?.downloads ?? []) {
-    if (dl.status === 'downloading') downloadByModel.set(dl.model_name, dl);
-  }
+  // Memo so the Map identity is stable across renders that don't change
+  // activeTasks — otherwise the cleanup effect below saw a fresh Map every
+  // render and re-fired on every 1 s poll tick.
+  const downloadByModel = useMemo(() => {
+    const m = new Map<string, ActiveDownloadTask>();
+    for (const dl of activeTasks?.downloads ?? []) {
+      if (dl.status === 'downloading') m.set(dl.model_name, dl);
+    }
+    return m;
+  }, [activeTasks]);
 
   // When a download disappears from activeTasks, it just finished — refetch
   // readiness immediately so the row flips to ✓ instead of waiting up to 5s
@@ -122,7 +128,7 @@ export function DictationReadinessChecklist({
       }
     }
     prevActive.current = current;
-  }, [activeTasks, queryClient, downloadByModel]);
+  }, [downloadByModel, queryClient]);
 
   const downloadMutation = useMutation({
     mutationFn: async ({ modelName }: { gate: ReadinessGate; modelName: string }) =>

app/src/components/ChordPicker/ChordPicker.tsx

@@ -65,8 +65,8 @@ export function ChordPicker({
       setCaptured(initialKeys);
       setUnsupportedAttempt(null);
       // Defer focus to the next paint so the dialog is mounted.
-      const t = window.setTimeout(() => captureRef.current?.focus(), 50);
-      return () => window.clearTimeout(t);
+      const timeoutId = window.setTimeout(() => captureRef.current?.focus(), 50);
+      return () => window.clearTimeout(timeoutId);
     }
     return;
   }, [open, initialKeys]);

app/src/components/ServerTab/CapturesPage.tsx

@@ -427,7 +427,7 @@ export function CapturesPage() {
                   {t('settings.captures.refinement.model.size17', { tail: t('settings.captures.refinement.model.tail.fast') })}
                 </SelectItem>
                 <SelectItem value="4B">
-                  {t('settings.captures.refinement.model.size4', { tail: t('settings.captures.refinement.model.tail.fullQuality') })}
+                  {t('settings.captures.refinement.model.size40', { tail: t('settings.captures.refinement.model.tail.fullQuality') })}
                 </SelectItem>
               </SelectContent>
             </Select>