chore: exclude build and native dirs from analyzer

[AmisKwok]

Summary / 摘要

Exclude generated build output and native platform folders from Dart analysis / 让 Dart 分析跳过构建产物与原生平台目录

Changes / 变更

• Add analyzer.exclude for build/**, android/** and ios/** in the root analysis_options.yaml and in example/analysis_options.yaml / 在根目录与 example 的 analysis_options.yaml 中新增 analyzer.exclude：build/**、android/**、ios/**
• Refresh transitive dev/test dependencies in example/pubspec.lock (matcher 0.12.20, meta 1.19.0, test_api 0.7.12, vector_math 2.4.3) / 刷新 example 的传递依赖锁文件（matcher 0.12.20、meta 1.19.0、test_api 0.7.12、vector_math 2.4.3）

Context / 背景

flutter analyze was walking generated build artifacts and the platform folders, which adds noise and slows down local and CI runs; these paths contain no hand-written Dart and should be skipped. / 之前的 flutter analyze 会扫描构建产物与平台目录，既拖慢本地与 CI 运行又带来噪音；这些路径不含手写的 Dart 代码，应当排除。

The lockfile refresh keeps the example app's dev/test toolchain current and makes CI analysis reproducible. / 锁文件刷新用于保持 example 的 dev/test 工具链较新，并让 CI 分析可复现。

No changes to lib/, so no CHANGELOG entry is required per the repo convention. / 本次未改动 lib/，按仓库约定无需写入 CHANGELOG。

Checklist / 检查项

• Title follows Conventional Commits / 标题符合约定式提交
• CI checks pass after merge / 合入后 CI 通过

Test plan

• flutter analyze reports no issues locally (verified before push) / 本地 flutter analyze 无问题（已推送前验证）
• CI Analyze & Test + Pana Score Check green (this PR touches analysis_options.yaml, a code path, so the real jobs run) / CI 的 Analyze & Test 与 Pana Score Check 通过（本 PR 触及 analysis_options.yaml，会触发完整任务）

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