feat: add achievement export

Automatically captures completed achievements during login and exports their IDs, including completed PlayStation trophies.

tests/test_achievement.py

@@ -0,0 +1,29 @@
+import struct
+import unittest
+
+from nte_history_exporter.decoder.achievement import (
+    ACHIEVEMENT_RECORD_MARKER,
+    extract_achievement_ids,
+    reassemble_tcp_segments,
+)
+
+
+class AchievementPacketTests(unittest.TestCase):
+    def test_extracts_only_completed_achievements(self):
+        header = ACHIEVEMENT_RECORD_MARKER + b"\0" * 4 + struct.pack("<I", 2) + b"\0" * 12
+        completed = b"\x0a\0\0\0Battle_30\0" + b"\0" * 8 + struct.pack("<Q", 1)
+        incomplete = b"\x13\0\0\0Playstation_035\0" + b"\0" * 16
+        decoded = header + completed + incomplete
+        extension = len(decoded) - 15
+        compressed = b"\xf0" + bytes([extension]) + decoded
+        frame = struct.pack("<I", 0) + b"\0" * 8 + struct.pack("<I", len(compressed)) + compressed
+        stream = struct.pack("<I", len(frame)) + frame
+
+        self.assertEqual(extract_achievement_ids(stream), ["Battle_30"])
+        self.assertEqual(extract_achievement_ids(b"\x01\0\0\0\0"), [])
+
+    def test_reassembles_tcp_data(self):
+        self.assertEqual(
+            reassemble_tcp_segments([(104, b"bar"), (100, b"foobar"), (100, b"foobar")]),
+            b"foobarr",
+        )