refactor(core): normalize core service naming

Standardize core service module and export names to reduce naming ambiguity and make imports predictable across runtime, tests, scripts, and docs.

src/core/services/overlay-bridge.test.ts

@@ -0,0 +1,77 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { KikuFieldGroupingChoice } from "../../types";
+import {
+  createFieldGroupingCallbackRuntime,
+  sendToVisibleOverlayRuntime,
+} from "./overlay-bridge";
+
+test("sendToVisibleOverlayRuntime restores visibility flag when opening hidden overlay modal", () => {
+  const sent: unknown[][] = [];
+  const restoreSet = new Set<"runtime-options" | "subsync">();
+  let visibleOverlayVisible = false;
+
+  const ok = sendToVisibleOverlayRuntime({
+    mainWindow: {
+      isDestroyed: () => false,
+      webContents: {
+        isLoading: () => false,
+        send: (...args: unknown[]) => {
+          sent.push(args);
+        },
+      },
+    } as unknown as Electron.BrowserWindow,
+    visibleOverlayVisible,
+    setVisibleOverlayVisible: (visible: boolean) => {
+      visibleOverlayVisible = visible;
+    },
+    channel: "runtime-options:open",
+    restoreOnModalClose: "runtime-options",
+    restoreVisibleOverlayOnModalClose: restoreSet,
+  });
+
+  assert.equal(ok, true);
+  assert.equal(visibleOverlayVisible, true);
+  assert.equal(restoreSet.has("runtime-options"), true);
+  assert.deepEqual(sent, [["runtime-options:open"]]);
+});
+
+test("createFieldGroupingCallbackRuntime cancels when overlay request cannot be sent", async () => {
+  let resolver: ((choice: KikuFieldGroupingChoice) => void) | null = null;
+  const callback = createFieldGroupingCallbackRuntime<
+    "runtime-options" | "subsync"
+  >({
+    getVisibleOverlayVisible: () => false,
+    getInvisibleOverlayVisible: () => false,
+    setVisibleOverlayVisible: () => {},
+    setInvisibleOverlayVisible: () => {},
+    getResolver: () => resolver,
+    setResolver: (next) => {
+      resolver = next;
+    },
+    sendToVisibleOverlay: () => false,
+  });
+
+  const result = await callback({
+    original: {
+      noteId: 1,
+      expression: "a",
+      sentencePreview: "a",
+      hasAudio: false,
+      hasImage: false,
+      isOriginal: true,
+    },
+    duplicate: {
+      noteId: 2,
+      expression: "b",
+      sentencePreview: "b",
+      hasAudio: false,
+      hasImage: false,
+      isOriginal: false,
+    },
+  });
+
+  assert.equal(result.cancelled, true);
+  assert.equal(result.keepNoteId, 0);
+  assert.equal(result.deleteNoteId, 0);
+});