refactor(subtitles): inject default rules into SubtitleRuleSet.resolve()

aggregates.py used to call SubtitleKnowledgeBase().default_rules() via a
DEFAULT_RULES() helper, which silently pulled the infrastructure layer
(YAML loader) into the domain on every resolve.

Make the dependency explicit: resolve() now takes the default rules as
a parameter, and the caller (the ManageSubtitles use case) loads them
from the KB once and passes them in. Domain stays I/O-free.

- Drop DEFAULT_RULES helper and the SubtitleKnowledgeBase import from
  alfred/domain/subtitles/aggregates.py
- SubtitleRuleSet.resolve(default_rules: SubtitleMatchingRules)
- manage_subtitles use case passes kb.default_rules() at the call site
- Tests use a local SubtitleMatchingRules stand-in instead of relying
  on KB defaults

tests/infrastructure/test_rule_repository.py

@@ -17,6 +17,7 @@ from pathlib import Path
 
 import yaml
 
+from alfred.domain.subtitles.value_objects import SubtitleMatchingRules
 from alfred.infrastructure.persistence.memory.ltm.components.subtitle_preferences import (
     SubtitlePreferences,
 )
@@ -25,6 +26,15 @@ from alfred.infrastructure.subtitle.rule_repository import (
     _filter_override,
 )
 
+# Stand-in for KB defaults, injected at resolve().
+_DEFAULT_RULES = SubtitleMatchingRules(
+    preferred_languages=["eng"],
+    preferred_formats=["srt"],
+    allowed_types=["standard"],
+    format_priority=["srt", "ass"],
+    min_confidence=0.7,
+)
+
 
 def _write(path: Path, data: dict) -> None:
     path.parent.mkdir(parents=True, exist_ok=True)
@@ -71,17 +81,17 @@ class TestLoad:
     def test_no_files_returns_global_default(self, tmp_path):
         repo = RuleSetRepository(tmp_path)
         rs = repo.load()
-        # Should resolve cleanly using the hardcoded defaults.
-        rules = rs.resolve()
-        assert rules.preferred_languages  # non-empty
-        assert rules.min_confidence > 0
+        # With no overrides, resolve returns the injected defaults unchanged.
+        rules = rs.resolve(_DEFAULT_RULES)
+        assert rules.preferred_languages == _DEFAULT_RULES.preferred_languages
+        assert rules.min_confidence == _DEFAULT_RULES.min_confidence
 
     def test_subtitle_preferences_override_base(self, tmp_path):
         prefs = SubtitlePreferences(
             languages=["jpn"], formats=["ass"], types=["standard"]
         )
         repo = RuleSetRepository(tmp_path)
-        rules = repo.load(subtitle_preferences=prefs).resolve()
+        rules = repo.load(subtitle_preferences=prefs).resolve(_DEFAULT_RULES)
         assert rules.preferred_languages == ["jpn"]
         assert rules.preferred_formats == ["ass"]
         assert rules.allowed_types == ["standard"]
@@ -92,7 +102,7 @@ class TestLoad:
             {"override": {"languages": ["spa"], "min_confidence": 0.95}},
         )
         repo = RuleSetRepository(tmp_path)
-        rules = repo.load().resolve()
+        rules = repo.load().resolve(_DEFAULT_RULES)
         assert rules.preferred_languages == ["spa"]
         assert rules.min_confidence == 0.95
 
@@ -102,7 +112,7 @@ class TestLoad:
             {"override": {"format_priority": ["ass", "srt"]}},
         )
         repo = RuleSetRepository(tmp_path)
-        rules = repo.load(release_group="KONTRAST").resolve()
+        rules = repo.load(release_group="KONTRAST").resolve(_DEFAULT_RULES)
         assert rules.format_priority == ["ass", "srt"]
 
     def test_full_three_level_chain(self, tmp_path):
@@ -119,7 +129,9 @@ class TestLoad:
             {"override": {"min_confidence": 0.99}},
         )
         repo = RuleSetRepository(tmp_path)
-        rules = repo.load(release_group="GRP", subtitle_preferences=prefs).resolve()
+        rules = repo.load(release_group="GRP", subtitle_preferences=prefs).resolve(
+            _DEFAULT_RULES
+        )
         # All three levels visible — local overrides on top
         assert rules.preferred_languages == ["jpn"]
         assert rules.format_priority == ["ass"]