Replace patchelf crack with Freeloader LD_PRELOAD approach

- Multi-stage Dockerfile: discover patterns from PMS binary (capstone),
  compile .so with zig (musl), layer onto lscr.io/linuxserver/plex
- Uses LD_PRELOAD instead of patchelf (which corrupts Plex's musl loader)
- Auto-discovery: broad structural patterns with string-anchored fallback
  (//feature) and relationship-based fallback (BITSET_REF within BS_INIT)
- hook.cpp uses __has_include for generated patterns with hardcoded fallbacks
- Custom wrapper.sh (no traffic_logger preload)
- Vendored Freeloader source (github.com/authrequest/Freeloader, AGPL-3.0)
- Removed stale plexmediaserver_crack.so binary
- Supports Plex 1.43.3+ (verified against 1.43.2 and 1.43.3)

Freeloader/plex_relay/tests/test_cache.py

@@ -0,0 +1,59 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+import os
+import stat
+
+import pytest
+
+from plex_relay.cache import HostKeyCache, parse_known_hosts
+from plex_relay.errors import HostKeyCacheError
+from plex_relay.models import HostKey
+
+
+def _entries():
+    return {
+        "[1.2.3.4]:443": HostKey("[1.2.3.4]:443", "ssh-ed25519", "AAAAfirst"),
+        "[5.6.7.8]:443": HostKey("[5.6.7.8]:443", "ssh-ed25519", "AAAAsecond"),
+    }
+
+
+def test_save_load_roundtrip(tmp_path):
+    cache = HostKeyCache(tmp_path / "relayHostKey.txt")
+    cache.save(_entries())
+    loaded = HostKeyCache(tmp_path / "relayHostKey.txt").load()
+    assert loaded == _entries()
+
+
+def test_save_is_sorted_and_blocked(tmp_path):
+    p = tmp_path / "relayHostKey.txt"
+    HostKeyCache(p).save(_entries())
+    text = p.read_text()
+    assert text.index("[1.2.3.4]") < text.index("[5.6.7.8]")
+    assert "# [1.2.3.4]:443\n[1.2.3.4]:443 ssh-ed25519 AAAAfirst\n" in text
+
+
+@pytest.mark.skipif(os.name != "posix", reason="POSIX file modes only")
+def test_save_is_0600(tmp_path):
+    p = tmp_path / "relayHostKey.txt"
+    HostKeyCache(p).save(_entries())
+    assert stat.S_IMODE(os.stat(p).st_mode) == 0o600
+
+
+def test_missing_file_loads_empty(tmp_path):
+    assert HostKeyCache(tmp_path / "nope.txt").load() == {}
+
+
+def test_malformed_file_is_rebuilt_empty(tmp_path):
+    p = tmp_path / "relayHostKey.txt"
+    p.write_text("not a comment\ngarbage line\n")
+    assert HostKeyCache(p).load() == {}
+    assert p.read_text() == ""
+
+
+@pytest.mark.parametrize("lines", [
+    ["data without marker"],
+    ["# marker only"],
+    ["# marker", "too many tokens here now"],
+])
+def test_parse_rejects_malformed(lines):
+    with pytest.raises(HostKeyCacheError):
+        parse_known_hosts(lines)