test: add real-world release fixtures (EASY bucket)

Captures 5 canonical releases from /mnt/testipool/downloads as parametrized
fixtures under tests/fixtures/releases/easy/. Each fixture declares the
release name, expected ParsedRelease fields, original tree, and the future
routing (library / torrents / seed_hardlinks) for the upcoming organize_media
refactor.

Today only the 'parsed' section is asserted; tree is materialized into a
tmp_path to catch typos. Routing is captured ahead of the planner work — it
becomes verifiable once organize_media lands.

Cases: back_in_action (movie), slow_horses_single_ep (TV single),
foundation_season_pack (S02 + .nfo noise), long_walk_with_noise (movie +
KONTRAST.TOP.txt), sinners_yts (YTS bracket-heavy + Subs/ dir).

Also tracks CHANGELOG.md under [Unreleased] / Added.

tests/fixtures/releases/conftest.py

@@ -0,0 +1,60 @@
+"""Fixture discovery and materialization helpers for release fixtures.
+
+Each fixture is a directory under ``tests/fixtures/releases/<bucket>/<case>/``
+containing one ``expected.yaml`` file. See ``releases/README.md`` for the
+schema.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from pathlib import Path
+
+import yaml
+
+FIXTURES_ROOT = Path(__file__).parent
+
+
+@dataclass(frozen=True)
+class ReleaseFixture:
+    """A loaded fixture, ready to be materialized into a temp dir."""
+
+    name: str  # "<bucket>/<case>", e.g. "easy/back_in_action"
+    path: Path  # directory containing expected.yaml
+    data: dict  # parsed YAML contents
+
+    @property
+    def release_name(self) -> str:
+        return self.data["release_name"]
+
+    @property
+    def expected_parsed(self) -> dict:
+        return self.data.get("parsed", {})
+
+    @property
+    def tree(self) -> list[str]:
+        return self.data.get("tree", [])
+
+    @property
+    def routing(self) -> dict:
+        return self.data.get("routing", {})
+
+    def materialize(self, root: Path) -> None:
+        """Create the fixture's ``tree`` as empty files/dirs under ``root``."""
+        for entry in self.tree:
+            target = root / entry
+            if entry.endswith("/"):
+                target.mkdir(parents=True, exist_ok=True)
+            else:
+                target.parent.mkdir(parents=True, exist_ok=True)
+                target.touch()
+
+
+def discover_fixtures() -> list[ReleaseFixture]:
+    """Find all ``expected.yaml`` files under FIXTURES_ROOT."""
+    fixtures = []
+    for yaml_path in sorted(FIXTURES_ROOT.glob("*/*/expected.yaml")):
+        data = yaml.safe_load(yaml_path.read_text())
+        name = f"{yaml_path.parent.parent.name}/{yaml_path.parent.name}"
+        fixtures.append(ReleaseFixture(name=name, path=yaml_path.parent, data=data))
+    return fixtures