refactor(shared): migrate mod.rs modules to path-style files

crates/shared/src/save.rs

@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+
+//! On-disk save format: the framing that persists modified chunks to region files.
+//!
+//! The format is built bottom-up. The smallest unit is the `SYNC` per-chunk [`record`], which wraps one [`crate::world::ChunkData`] in a self-describing, compressed frame. Region-level framing (the `SYNR` file and its header table) is layered on top of it. All parsing treats on-disk bytes as untrusted and reports failures through [`SaveError`].
+
+mod cursor;
+mod error;
+pub mod record;
+pub mod region;
+
+pub use error::SaveError;

crates/shared/src/world.rs

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+
+//! Core data structures representing the voxel world.
+//!
+//! The module is split by concept: [`BlockId`] material handles, the [`Chunk`] storage forms, chunk-space coordinates in [`ChunkPos`], and precision-safe entity positions in [`EntityPos`]. Each lives in its own submodule and is re-exported here so callers continue to refer to `shared::world::<Type>` regardless of the internal layout.
+
+mod block;
+mod chunk;
+mod chunk_data;
+mod coords;
+mod entity;
+
+pub use block::BlockId;
+pub use chunk::{Chunk, PalettedChunk};
+pub use chunk_data::ChunkData;
+pub use coords::ChunkPos;
+pub use entity::EntityPos;
+
+/// The size of a chunk along one axis in blocks.
+pub const CHUNK_SIZE: usize = 32;
+/// The total number of blocks within a single chunk.
+pub const CHUNK_VOLUME: usize = CHUNK_SIZE * CHUNK_SIZE * CHUNK_SIZE;