Improve startup dictionary progress and fix overlay/plugin input handlin

- show a dedicated startup OSD "building" phase for character dictionary sync
- forward bare `Tab` from visible overlay to mpv so AniSkip works while focused
- fix Windows plugin env override resolution for `SUBMINER_BINARY_PATH`

src/main/runtime/overlay-window-factory-main-deps.test.ts

@@ -16,12 +16,14 @@ test('overlay window factory main deps builders return mapped handlers', () => {
     setOverlayDebugVisualizationEnabled: (enabled) => calls.push(`debug:${enabled}`),
     isOverlayVisible: (kind) => kind === 'visible',
     tryHandleOverlayShortcutLocalFallback: () => false,
+    forwardTabToMpv: () => calls.push('forward-tab'),
     onWindowClosed: (kind) => calls.push(`closed:${kind}`),
   });
 
   const overlayDeps = buildOverlayDeps();
   assert.equal(overlayDeps.isDev, true);
   assert.equal(overlayDeps.isOverlayVisible('visible'), true);
+  overlayDeps.forwardTabToMpv();
 
   const buildMainDeps = createBuildCreateMainWindowMainDepsHandler({
     createOverlayWindow: () => ({ id: 'visible' }),
@@ -37,5 +39,5 @@ test('overlay window factory main deps builders return mapped handlers', () => {
   const modalDeps = buildModalDeps();
   modalDeps.setModalWindow(null);
 
-  assert.deepEqual(calls, ['set-main', 'set-modal']);
+  assert.deepEqual(calls, ['forward-tab', 'set-main', 'set-modal']);
 });