docs(changelog): summarize refactor/domain-io-extraction work block

CHANGELOG.md

@@ -112,6 +112,37 @@ callers).
 
 ### Internal
 
+- **Domain I/O extraction** (`refactor/domain-io-extraction`): the domain
+  layer no longer performs subprocess calls, filesystem scans, or YAML
+  loading. Achieved in a series of focused commits:
+  - **Knowledge YAML loaders moved to infrastructure**:
+    `alfred/domain/release/knowledge.py`,
+    `alfred/domain/shared/knowledge/language_registry.py`, and
+    `alfred/domain/subtitles/knowledge/{base,loader}.py` relocated to
+    `alfred/infrastructure/knowledge/`. Re-exports were dropped — callers
+    import directly from the new location.
+  - **`MediaProber` and `FilesystemScanner` Protocol ports** introduced at
+    `alfred/domain/shared/ports/` with frozen-dataclass DTOs
+    (`SubtitleStreamInfo`, `FileEntry`). `SubtitleIdentifier` and
+    `PatternDetector` are now constructor-injected with concrete adapters
+    (`FfprobeMediaProber` wrapping `subprocess.run(ffprobe)` and
+    `PathlibFilesystemScanner` wrapping `pathlib`). No more direct
+    `subprocess`/`pathlib` usage from the subtitle domain services.
+  - **Live filesystem methods removed from VOs and entities**:
+    `FilePath.exists()` / `.is_file()` / `.is_dir()` deleted —
+    `FilePath` is now a pure address VO. `Movie.has_file()` and
+    `Episode.is_downloaded()` dropped. Callers either rely on a prior
+    detection step or use try/except over pre-checks (eliminates
+    TOCTOU races).
+  - **`SubtitlePlacer` moved to the application layer** at
+    `alfred/application/subtitles/placer.py` — it performs `os.link`
+    I/O, which doesn't belong in the domain. Pre-checks replaced with
+    try/except for `FileNotFoundError`/`FileExistsError`.
+  - **`SubtitleRuleSet.resolve()` no longer reaches into the knowledge
+    base**: the implicit `DEFAULT_RULES()` helper is gone, replaced by
+    an explicit `default_rules: SubtitleMatchingRules` parameter. The
+    `ManageSubtitles` use case loads defaults from the KB once and
+    passes them in.
 - **`to_dot_folder_name(title)` helper** in
   `alfred/domain/shared/value_objects.py` — extracts the
   `re.sub(r"[^\w\s\.\-]", "", title).replace(" ", ".")` pattern that was