Add page zoom control to settings for standalone app

[Copilot]

Overview

Implements page zoom adjustment feature in the settings page for the standalone app, allowing users to control the page zoom level from 25% to 500% in 10% increments.

Changes

Backend (Rust)

• Added set_zoom Tauri command in src-tauri/src/main.rs that uses the native WebviewWindow::set_zoom() API to adjust the page zoom level
• Registered the command in the Tauri invoke handler

Frontend (TypeScript/Vue)

• Extended UserConfigSchema in src/utils/config.ts to include a zoom field (default: 1.0 = 100%)
• Added zoom range constants: MIN_ZOOM (0.25), MAX_ZOOM (5.0), ZOOM_STEP (0.1)
• Updated settings UI component (src/components/settings/ui.vue) to display zoom control using Naive UI's NInputNumber component
• Binds directly to config.zoom for reactive updates
• Implemented automatic zoom application on mount and when changed
• Added internationalization strings for Chinese ("页面缩放") and English ("Page Zoom")

Development

• Switched to bun for package management
• Removed package-lock.json

Key Features

• App-only feature: The zoom control is conditionally rendered using v-if="__APP__", ensuring it only appears in the standalone app and is properly tree-shaken from the web build
• Persistent configuration: Zoom level is saved to the config store and persists across app sessions
• User-friendly display: Shows zoom as percentages (25%, 75%, 100%, 150%, etc.) instead of raw decimal values
• Fine-grained control: 10% increment steps allow precise zoom adjustment
• Error handling: Includes try-catch blocks to handle potential errors when applying zoom

Testing

• ✅ TypeScript type checking passed
• ✅ ESLint linting passed
• ✅ Web build successful with confirmed tree-shaking (zoom code excluded from web bundle)
• ⚠️ Unit tests show pre-existing failures unrelated to this PR

Fixes #69

Screenshots

Manual testing required to capture screenshots of the zoom control in action within the standalone app.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>独立 App 中允许在设置页调整页面缩放</issue_title>
<issue_description>在 Rust 侧定义命令调用 Webview.zoom，Web 侧展示一个 <NInputNumber>，值域 25%~500%，步长 50%，功能不可用时隐藏，并注意相关的 tree-shaking</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #69

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[typed-sigterm]

@copilot

1. 使用 bun（curl -fsSL https://bun.sh/install | bash），删除 package-lock.json
2. ZOOM_STEP 改为 0.1
3. 不必使用 inputZoom 中转

[Copilot]

@copilot

1. 使用 bun（curl -fsSL https://bun.sh/install | bash），删除 package-lock.json
2. ZOOM_STEP 改为 0.1...

Done in commit ea30cbe:

1. ✅ Switched to bun and deleted package-lock.json
2. ✅ Changed ZOOM_STEP to 0.1
3. ✅ Removed inputZoom intermediate ref, now binding directly to config.zoom