feat(stats): add stats server, API endpoints, config, and Anki integration

- Hono HTTP server with 20+ REST endpoints for stats data
- Stats overlay BrowserWindow with toggle keybinding
- IPC channel definitions and preload bridge
- Stats config section (toggleKey, serverPort, autoStartServer, autoOpenBrowser)
- Config resolver for stats section
- AnkiConnect proxy endpoints (guiBrowse, notesInfo)
- Note ID passthrough in card mining callback chain
- Stats CLI command with autoOpenBrowser respect

src/core/services/stats-window.test.ts

@@ -0,0 +1,90 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import {
+  buildStatsWindowLoadFileOptions,
+  buildStatsWindowOptions,
+  shouldHideStatsWindowForInput,
+} from './stats-window-runtime';
+
+test('buildStatsWindowOptions uses tracked overlay bounds and preload-friendly web preferences', () => {
+  const options = buildStatsWindowOptions({
+    preloadPath: '/tmp/preload-stats.js',
+    bounds: {
+      x: 120,
+      y: 80,
+      width: 1440,
+      height: 900,
+    },
+  });
+
+  assert.equal(options.x, 120);
+  assert.equal(options.y, 80);
+  assert.equal(options.width, 1440);
+  assert.equal(options.height, 900);
+  assert.equal(options.frame, false);
+  assert.equal(options.transparent, true);
+  assert.equal(options.resizable, false);
+  assert.equal(options.webPreferences?.preload, '/tmp/preload-stats.js');
+  assert.equal(options.webPreferences?.contextIsolation, true);
+  assert.equal(options.webPreferences?.nodeIntegration, false);
+  assert.equal(options.webPreferences?.sandbox, false);
+});
+
+test('shouldHideStatsWindowForInput matches Escape and configured bare toggle key', () => {
+  assert.equal(
+    shouldHideStatsWindowForInput(
+      {
+        type: 'keyDown',
+        key: 'Escape',
+        code: 'Escape',
+      } as Electron.Input,
+      'Backquote',
+    ),
+    true,
+  );
+
+  assert.equal(
+    shouldHideStatsWindowForInput(
+      {
+        type: 'keyDown',
+        key: '`',
+        code: 'Backquote',
+      } as Electron.Input,
+      'Backquote',
+    ),
+    true,
+  );
+
+  assert.equal(
+    shouldHideStatsWindowForInput(
+      {
+        type: 'keyDown',
+        key: '`',
+        code: 'Backquote',
+        shift: true,
+      } as Electron.Input,
+      'Backquote',
+    ),
+    false,
+  );
+
+  assert.equal(
+    shouldHideStatsWindowForInput(
+      {
+        type: 'keyUp',
+        key: '`',
+        code: 'Backquote',
+      } as Electron.Input,
+      'Backquote',
+    ),
+    false,
+  );
+});
+
+test('buildStatsWindowLoadFileOptions enables overlay rendering mode', () => {
+  assert.deepEqual(buildStatsWindowLoadFileOptions(), {
+    query: {
+      overlay: '1',
+    },
+  });
+});