docs: drop process records and internal implementation docs

Keep only install, usage, development-workflow and architecture-boundary
documents; remove the one-off refactor plans, audits and ledgers that had
already served their purpose.

- delete docs/refactor plus the agent API surface audit generator and its
  drift-only tests; the fixed route registry remains the source of truth
- delete internal implementation notes (agent, music, notification, transfer,
  subscription activity, docker startup, V3t runtime governance)
- delete site adapter capture/release shims and the ADR records; external
  links point at MoviePilot-Site-Collector instead
- keep docs/architecture-overview.md and gate its dependency and event
  figures against the generated fixtures
- drop doc-only assertions from the architecture baseline test and retarget
  remaining references at code and rule documents

docs/cli.md

@@ -533,7 +533,7 @@ moviepilot config describe API_TOKEN --show-secrets
 - `AMLL_BASE_URL` 默认使用无需 API Key 的 AMLL TTML API，也可指向兼容原生接口的自建实例。来源优先按 ISRC 查询，再严格核对歌曲、艺术家及已有专辑信息；下载的 TTML 主唱时间轴转换为 Lyricsfile 和 LRC，限流时短暂冷却并让其他歌词来源继续处理
 - `THEAUDIODB_API_KEY` 用于音乐元数据及纯文本歌词兜底，默认 `123` 为官方公开 V1 Key；额外歌词来源可通过插件提供，接入方式见[歌词插件开发说明](https://github.com/jxxghp/MoviePilot-Plugins/blob/main/docs/faq/21-register-lyrics-provider.md)
 - `MUSIC_METADATA_TO_SIMPLIFIED` 默认开启；开启后会将识别结果中的曲名、艺术家、专辑和分类等标准音乐元数据转换为简体中文，不转换歌词与来源原始响应
-- `MUSIC_COVER_FILE_PATTERNS` 控制同目录音乐封面的文件名匹配与选择顺序，逗号分隔、大小写不敏感；附加文件整理和内嵌封面回退共用此配置，详见[音乐本地封面](music-covers.md)
+- `MUSIC_COVER_FILE_PATTERNS` 控制同目录音乐封面的文件名匹配与选择顺序，逗号分隔、大小写不敏感；附加文件整理和内嵌封面回退共用此配置
 - `MUSIC_LYRICS_TO_SIMPLIFIED` 默认关闭，独立控制生成的 `.lrc` / `.txt` 歌词正文转简体；时间轴、LRC 标签及来源 Lyricsfile 保持原样。已有歌词仍遵循原刮削策略，需要转换时选择“总是刮削”重新刮削
 - `MUSIC_RELEASE_REGION_PRIORITY` 与 `MUSIC_RELEASE_SCRIPT_PRIORITY` 分别使用逗号分隔的 ISO 3166-1 地区代码和 ISO 15924 文字代码；仅在 MusicBrainz 候选结构同样可信时作为发行版本排序依据，最多使用前三项
 - `config describe` 显示单个配置项的类型、默认值和当前值