fix: stabilize item display metadata packing

[mvanhorn]

Order each Bukkit NMS adapter's reflected EntityDataAccessor collection by accessor id before any existing positional selection, keeping the current field mapping and packet-building behavior otherwise unchanged. Apply the same minimal change across all maintained Bukkit NMS versions because these duplicated adapters are required to remain behaviorally equivalent; the Fabric implementation already uses named mixin accessors and is out of scope. Add a focused v26_R2 regression test that checks accessor ordering and the complete TransformationData.pack() output, including unique expected ids and the correct serializer/value category for interpolation delay, integer duration, translation, scale, and rotation. BetterModel 3.3.0 can send an ItemDisplay metadata entry whose field id is the integer interpolation-duration field while its serializer and payload are for a float, causing vanilla 26.2 clients to disconnect with a network protocol error. The reported failure is intermittent under rapid model spawn/despawn load, but the field/type pair and the v26_R2 transformation packing path are concrete. Bukkit NMS adapters currently collect EntityDataAccessor fields in raw Class.getDeclaredFields() order and then use positional indexes to select duration, translation, scale, and rotation accessors. That JVM field order is not a supported contract, while the accessors' numeric metadata ids provide the stable ordering the packet format requires.

Testing: With reflected Display accessors returned from accessors(), assert their ids are strictly ordered so positional selection cannot bind a later float accessor to the interpolation-duration slot; Pack a transformation with duration 20 and non-default translation, scale, and rotation; assert the duration entry uses the interpolation-duration id and integer serializer/value rather than a float serializer/value.

Fixes #405