feat: support configurable upload timeout and 2GB files

[CritasWang]

Summary

• add an elegant upload-timeout control to the upload panel, defaulting to 30 minutes
• persist the selected timeout locally and apply it per upload request
• show upload progress and timeout-specific feedback
• raise frontend and backend upload limits to 2GB
• update English and Chinese API, deployment, and user documentation

Validation

• pnpm build
• pnpm exec oxlint .
• pnpm exec oxfmt --check src/components/tsfile/FileUpload.vue src/api/tsfile/file.ts
• mvn test -Dspotless.check.skip=true (285 tests, 0 failures/errors, 17 skipped)
• browser checks on desktop and 375px mobile layouts, including timeout persistence and cleared-input normalization
• locale JSON, YAML parsing, and git diff --check

Note

mvn verify reaches packaging successfully but the repository-wide Spotless check currently reports pre-existing formatting violations in 35 Java files unrelated to this change.