fix(stats): drain full write queue before anime merge/move rebuilds

- Replace single flushNow() with drainWriteQueue loop so forced telemetry appended after a full batch isn't left unwritten before merge/move/rebuild summaries recompute
- Add dialog a11y to AnimeMergeDialog/LibraryEntryPicker: aria-modal, labelled headings, alert roles for errors, labelled search input, close button labels

stats/src/components/anime/LibraryEntryPicker.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useMemo, useRef, useState } from 'react';
+import { useEffect, useId, useMemo, useRef, useState } from 'react';
 import { apiClient } from '../../lib/api-client';
 import { formatDuration } from '../../lib/formatters';
 import { AnimeCoverImage } from './AnimeCoverImage';
@@ -28,6 +28,8 @@ export function LibraryEntryPicker({
   const [loadFailed, setLoadFailed] = useState(false);
   const [query, setQuery] = useState(initialQuery);
   const inputRef = useRef<HTMLInputElement>(null);
+  const headingId = useId();
+  const searchId = useId();
 
   useEffect(() => {
     inputRef.current?.focus();
@@ -62,40 +64,56 @@ export function LibraryEntryPicker({
     <div className="fixed inset-0 z-50 flex items-start justify-center pt-[10vh]" onClick={onClose}>
       <div className="absolute inset-0 bg-ctp-crust/70 backdrop-blur-[2px]" />
       <div
+        role="dialog"
+        aria-modal="true"
+        aria-labelledby={headingId}
         className="relative bg-ctp-base border border-ctp-surface1 rounded-xl shadow-2xl w-full max-w-lg max-h-[70vh] flex flex-col animate-fade-in"
         onClick={(e) => e.stopPropagation()}
       >
         <div className="p-4 border-b border-ctp-surface1">
           <div className="flex items-center justify-between mb-3">
-            <h3 className="text-sm font-semibold text-ctp-text">{heading}</h3>
+            <h3 id={headingId} className="text-sm font-semibold text-ctp-text">
+              {heading}
+            </h3>
             <button
               type="button"
               onClick={onClose}
+              aria-label="Close"
               className="text-ctp-overlay2 hover:text-ctp-text text-lg leading-none"
             >
               {'✕'}
             </button>
           </div>
+          <label htmlFor={searchId} className="sr-only">
+            Search library
+          </label>
           <input
             ref={inputRef}
+            id={searchId}
             type="text"
             value={query}
             onChange={(e) => setQuery(e.target.value)}
             placeholder="Search library..."
             className="w-full bg-ctp-surface0 border border-ctp-surface1 rounded-lg px-3 py-2 text-sm text-ctp-text placeholder:text-ctp-overlay2 focus:outline-none focus:border-ctp-blue"
           />
-          {error ? <div className="text-xs text-ctp-red mt-2">{error}</div> : null}
+          {error ? (
+            <div role="alert" className="text-xs text-ctp-red mt-2">
+              {error}
+            </div>
+          ) : null}
         </div>
 
         <div className="flex-1 overflow-y-auto p-2">
           {entries === null && <div className="text-xs text-ctp-overlay2 p-3">Loading...</div>}
           {loadFailed && (
-            <div className="text-xs text-ctp-red p-3">
+            <div role="alert" className="text-xs text-ctp-red p-3">
               Could not load the library. Close this dialog and try again.
             </div>
           )}
           {!loadFailed && entries !== null && visible.length === 0 && (
-            <div className="text-xs text-ctp-overlay2 p-3">No other titles</div>
+            <div className="text-xs text-ctp-overlay2 p-3">
+              {query.trim() ? 'No matches' : 'No other titles'}
+            </div>
           )}
           {visible.map((entry) => (
             <button