Wrong Yellow Matrix V2.2 Paint Builder

Source: source_01.nbt parsed at build time.
Fences: 23 cells. Components: 5.
Corners are normalized as crosses.

Main changes:
- no runtime recursive split scan; the connected fence component is enqueued in one deterministic pass.
- the physical source NBT is never placed in the world, so it cannot remain visible on the roof.
- split networks behave like a paint bucket: discovering any fence cell enqueues the whole connected network.
- one active builder, one 16x48x8/top segment every two ticks, top-down.
- air cells remain deterministic 50/50 well vs monoroom.

Limitation: changing source_01.nbt now requires regenerating this compiled pack. This is intentional for this stable test branch; it removes the fragile in-game NBT reader from V2.1.

Runtime marker version: br_giga_matrix_v = 3, so V2/V2.1 markers are ignored.
