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-runtime.ts

@@ -0,0 +1,64 @@
+import type { BrowserWindowConstructorOptions } from 'electron';
+import type { WindowGeometry } from '../../types';
+
+const DEFAULT_STATS_WINDOW_WIDTH = 900;
+const DEFAULT_STATS_WINDOW_HEIGHT = 700;
+
+function isBareToggleKeyInput(input: Electron.Input, toggleKey: string): boolean {
+  return (
+    input.type === 'keyDown' &&
+    input.code === toggleKey &&
+    !input.control &&
+    !input.alt &&
+    !input.meta &&
+    !input.shift &&
+    !input.isAutoRepeat
+  );
+}
+
+export function shouldHideStatsWindowForInput(
+  input: Electron.Input,
+  toggleKey: string,
+): boolean {
+  return (
+    (input.type === 'keyDown' && input.key === 'Escape') ||
+    isBareToggleKeyInput(input, toggleKey)
+  );
+}
+
+export function buildStatsWindowOptions(options: {
+  preloadPath: string;
+  bounds?: WindowGeometry | null;
+}): BrowserWindowConstructorOptions {
+  return {
+    x: options.bounds?.x,
+    y: options.bounds?.y,
+    width: options.bounds?.width ?? DEFAULT_STATS_WINDOW_WIDTH,
+    height: options.bounds?.height ?? DEFAULT_STATS_WINDOW_HEIGHT,
+    frame: false,
+    transparent: false,
+    alwaysOnTop: true,
+    resizable: false,
+    skipTaskbar: true,
+    hasShadow: false,
+    focusable: true,
+    acceptFirstMouse: true,
+    fullscreenable: false,
+    backgroundColor: '#1e1e2e',
+    show: false,
+    webPreferences: {
+      nodeIntegration: false,
+      contextIsolation: true,
+      preload: options.preloadPath,
+      sandbox: false,
+    },
+  };
+}
+
+export function buildStatsWindowLoadFileOptions(): { query: Record<string, string> } {
+  return {
+    query: {
+      overlay: '1',
+    },
+  };
+}