chore: archive refactor milestones and remove structural quality-gates task

- Remove structural quality gates task and references from task-27 roadmap.
- Remove structural-gates-adjacent work from scripts/positioning cleanup context, including check-main-lines adjustments.
- Archive completed backlog tasks 11 and 27.7 by moving them to completed directory.
- Finish task-27.5 module split by moving/anonymizing anki-integration and renderer positioning files into their dedicated directories and updating paths.

src/anki-integration/duplicate.ts

@@ -0,0 +1,102 @@
+export interface NoteField {
+  value: string;
+}
+
+export interface NoteInfo {
+  noteId: number;
+  fields: Record<string, NoteField>;
+}
+
+export interface DuplicateDetectionDeps {
+  findNotes: (
+    query: string,
+    options?: { maxRetries?: number },
+  ) => Promise<unknown>;
+  notesInfo: (noteIds: number[]) => Promise<unknown>;
+  getDeck: () => string | null | undefined;
+  resolveFieldName: (noteInfo: NoteInfo, preferredName: string) => string | null;
+  logWarn: (message: string, error: unknown) => void;
+}
+
+export async function findDuplicateNote(
+  expression: string,
+  excludeNoteId: number,
+  noteInfo: NoteInfo,
+  deps: DuplicateDetectionDeps,
+): Promise<number | null> {
+  let fieldName = "";
+  for (const name of Object.keys(noteInfo.fields)) {
+    if (
+      ["word", "expression"].includes(name.toLowerCase()) &&
+      noteInfo.fields[name].value
+    ) {
+      fieldName = name;
+      break;
+    }
+  }
+  if (!fieldName) return null;
+
+  const escapedFieldName = escapeAnkiSearchValue(fieldName);
+  const escapedExpression = escapeAnkiSearchValue(expression);
+  const deckPrefix = deps.getDeck()
+    ? `"deck:${escapeAnkiSearchValue(deps.getDeck()!)}" `
+    : "";
+  const query = `${deckPrefix}"${escapedFieldName}:${escapedExpression}"`;
+
+  try {
+    const noteIds = (await deps.findNotes(query, { maxRetries: 0 }) as number[]);
+    return await findFirstExactDuplicateNoteId(
+      noteIds,
+      excludeNoteId,
+      fieldName,
+      expression,
+      deps,
+    );
+  } catch (error) {
+    deps.logWarn("Duplicate search failed:", error);
+    return null;
+  }
+}
+
+function findFirstExactDuplicateNoteId(
+  candidateNoteIds: number[],
+  excludeNoteId: number,
+  fieldName: string,
+  expression: string,
+  deps: DuplicateDetectionDeps,
+): Promise<number | null> {
+  const candidates = candidateNoteIds.filter((id) => id !== excludeNoteId);
+  if (candidates.length === 0) {
+    return Promise.resolve(null);
+  }
+
+  const normalizedExpression = normalizeDuplicateValue(expression);
+  const chunkSize = 50;
+  return (async () => {
+    for (let i = 0; i < candidates.length; i += chunkSize) {
+      const chunk = candidates.slice(i, i + chunkSize);
+      const notesInfoResult = (await deps.notesInfo(chunk)) as unknown[];
+      const notesInfo = notesInfoResult as NoteInfo[];
+      for (const noteInfo of notesInfo) {
+        const resolvedField = deps.resolveFieldName(noteInfo, fieldName);
+        if (!resolvedField) continue;
+        const candidateValue = noteInfo.fields[resolvedField]?.value || "";
+        if (normalizeDuplicateValue(candidateValue) === normalizedExpression) {
+          return noteInfo.noteId;
+        }
+      }
+    }
+    return null;
+  })();
+}
+
+function normalizeDuplicateValue(value: string): string {
+  return value.replace(/\s+/g, " ").trim();
+}
+
+function escapeAnkiSearchValue(value: string): string {
+  return value
+    .replace(/\\/g, "\\\\")
+    .replace(/"/g, '\\"')
+    .replace(/([:*?()[\]{}])/g, "\\$1");
+}