feat: v3.0.2 - i18n, audio-only flow, task control, UX polish

[doomsday616]

feat: v3.0.2 - i18n, audio-only flow, task control, UX polish

Bumps version to 3.0.2.
版本号升至 3.0.2。

主要内容 / Major themes:

i18n

• Browser language auto-detection (Accept-Language) on first load,
  with a top-right language selector overriding the choice per session.
  首次加载根据浏览器 Accept-Language 自动识别语言；右上角语言选择器可按会话覆盖。
• Sidebar duplicate language selector removed.
  移除侧边栏重复的语言选择器。
• Routes display_language through query params + session_state, with
  config.yaml as a fallback only.
  display_language 改为优先走 query params + session_state，config.yaml 仅作兜底。
• Adds normalize_language_code() to map zh / zh-CN / zh-HK / zh-Hant /
  variants to the supported set.
  新增 normalize_language_code()，把 zh / zh-CN / zh-HK / zh-Hant 等变体统一映射到受支持的语言。
• Translates previously hard-coded UI strings: WhisperX runtime, TTS
  engine names, Voice / 302ai API / ElevenLabs API labels, "Star on
  GitHub" button, YouTube resolution "Best".
  翻译之前硬编码的 UI 文案：WhisperX runtime、TTS 引擎名、Voice / 302ai API / ElevenLabs API 标签、"Star on GitHub" 按钮、YouTube 分辨率 "Best"。
• Fixes 'here' link text leaking English in zh-CN / zh-HK welcome
  string.
  修复欢迎语在简中/繁中里 "here" 链接文字仍为英文的问题。
• Adds CSS overlay for the file_uploader internals (Streamlit has no
  official i18n for these) covering "Drag and drop file here",
  "Limit ... per file" and "Browse files" labels.
  通过 CSS 覆盖 file_uploader 内部文案（Streamlit 官方未提供 i18n），包括 "Drag and drop file here"、"Limit ... per file"、"Browse files"。
• Hides Streamlit developer toolbar (client.toolbarMode = "viewer")
  and disables the file watcher (server.fileWatcherType = "none") so
  "File change / Rerun / Always rerun" prompts no longer appear.
  隐藏 Streamlit 开发者工具栏（client.toolbarMode = "viewer"），关闭文件监听（server.fileWatcherType = "none"），避免出现 "File change / Rerun / Always rerun" 英文提示。
• Fills missing translation keys across en / zh-CN / zh-HK / es / fr /
  ja / ru.
  补全 en / zh-CN / zh-HK / es / fr / ja / ru 七种语言中缺失的翻译键。

Audio-only input flow / 纯音频输入流程

• Adds output/input_manifest.json written by the upload / YouTube
  download path, recording the original media type. find_media_file()
  now reads the manifest first, so generated artefacts (dub.mp3,
  normalized_dub.wav) no longer poison detection.
  上传 / YouTube 下载后写入 output/input_manifest.json 记录原始媒体类型。find_media_file() 优先读 manifest，避免生成产物（dub.mp3、normalized_dub.wav）污染识别。
• find_audio_files() now skips generated audio names.
  find_audio_files() 自动跳过生成产物文件名。
• find_media_file() distinguishes "no media" vs "multiple media"
  errors instead of silently falling back.
  find_media_file() 区分"无媒体"和"多个媒体"两种错误，不再静默 fallback。
• Sidebar no longer persistently writes burn_subtitles = false when
  the input is audio; the toggle is only disabled in the UI.
  音频输入时不再持久化写入 burn_subtitles = false，只在 UI 层禁用开关。
• Main pipeline now flows download -> subtitles -> (optional) dubbing,
  only showing the dubbing section after subtitles are done AND the
  input is not audio.
  主流程改为：下载 → 字幕 →（可选）配音；只有字幕完成且输入不是音频时才显示配音段。
• Adds prepare_audio_for_asr() so audio-only inputs are normalized to
  16k / mono / mp3 without going through video conversion.
  新增 prepare_audio_for_asr()，纯音频输入直接归一化为 16k / 单声道 / mp3，不再经过视频转换。
• Removes the obsolete convert_audio_to_video() placeholder path.
  移除已废弃的 convert_audio_to_video() 占位路径。

Task control (pause / resume / stop) / 任务控制（暂停 / 继续 / 停止）

• TaskRunner gains a class-level _current pointer and TaskRunner.check_cancel()
  so long-running core loops can cooperatively cancel.
  TaskRunner 新增类级 _current 指针和 TaskRunner.check_cancel()，让长循环可以协作式取消。
• Adds core.utils.check_cancel() wrapper, imported via the existing
  from core.utils import * pattern.
  新增 core.utils.check_cancel() 包装，沿用现有 from core.utils import * 导入方式。
• Inserts check_cancel() into the hot loops: ASR segment loop,
  translate parallel loop, TTS warmup / parallel collection / chunk
  merge, audio segment merge, translate_lines entry. Parallel loops
  also cancel pending futures on stop.
  在热点循环里插入 check_cancel()：ASR 分段循环、翻译并行循环、TTS warmup / 并行收集 / chunk 合并、音频段合并、translate_lines 入口。并行循环在 stop 时主动 cancel 未启动的 futures。

Done markers and completion detection / 完成标记与状态判断

• Adds output/.subtitle_done and output/.dubbing_done markers written
  by the runner as the last step of each stage.
  TaskRunner 在每个阶段最后一步写入 output/.subtitle_done 和 output/.dubbing_done 标记。
• text_done / audio_done now prefer the marker, falling back to a full
  outputs-present check, so half-failed runs are no longer mistaken
  for completion.
  text_done / audio_done 优先读标记，没有则回落到"所有最终产物齐全"检查，避免半失败被误判为完成。
• Subtitle length tuning controls (max_split_length, subtitle.max_length)
  surfaced in an expandable section above "Start Processing Subtitles",
  with suggested ranges and a "Restore defaults" button.
  在"开始处理字幕"上方加入折叠的字幕长度微调（max_split_length、subtitle.max_length），含建议范围和"恢复默认"按钮。

Robustness fixes / 健壮性修复

• ElevenLabs ASR: elev2whisper() now always emits word-level
  timestamps; process_transcription() tolerates segments without
  words by synthesizing one from the segment text.
  ElevenLabs ASR：elev2whisper() 始终输出词级时间戳；process_transcription() 对没有 words 的 segment 用 segment 文本合成一个，避免 KeyError。
• download_video_section now surfaces detection errors (e.g. multiple
  media files in output/) with a clear message and a "Clear output and
  reselect" button, instead of silently falling back to the upload
  view.
  download_video_section 在媒体识别失败（例如 output/ 里有多个媒体）时显示明确错误和"清空输出并重新选择"按钮，不再静默回到上传界面。
• Re-upload of the same file is detected via session_state, avoiding
  an infinite rerun loop.
  通过 session_state 识别同一文件的重复上传，避免无限 rerun 循环。
• give_star_button rewritten to a plain string template; previous
  f-string broke on the literal { in the embedded CSS.
  give_star_button 改写为普通字符串模板；原 f-string 因内嵌 CSS 里的 { 报错。

Tooling and config / 工具与配置

• OneKeyStart.bat consolidated: auto-detects .venv (uv install) or
  falls back to the legacy Conda env "videolingo"; OneKeyStart_uv.bat
  removed.
  合并 OneKeyStart.bat：自动检测 .venv（uv 安装）或回落到旧的 Conda 环境 "videolingo"；删除 OneKeyStart_uv.bat。
• Logs now go to logs/videolingo_.log instead of the
  project root.
  日志写入 logs/videolingo_.log，不再散落在项目根目录。
• .streamlit/config.toml: client.toolbarMode = "viewer",
  server.fileWatcherType = "none", server.maxUploadSize preserved.
  .streamlit/config.toml：client.toolbarMode = "viewer"，server.fileWatcherType = "none"，保留 server.maxUploadSize。
• .gitignore: ignores logs/, videolingo_.log, AGENTS.md, pr-body.md.
  .gitignore：忽略 logs/、videolingo_.log、AGENTS.md、pr-body.md。
• setup.py + config.yaml header bumped to 3.0.2.
  setup.py 与 config.yaml 顶部版本号统一升至 3.0.2。

No new dependencies. No CLI behavior changes.
未引入新依赖。CLI 行为无变更。