Expand voxel gameplay, lighting, full-height streaming and world imports

Add shared Rust/WASM physics, worker meshing and diagnostics, 64-chunk full-height streaming, atlas texture support, and baseline world import. Document the current implementation and include the supplied in-game lobby screenshot.

docs/interop.md

@@ -14,6 +14,9 @@ cargo build --release -p shacraft-compat -p shacraft-server
 # Import a copy of a stopped Java world into a new native store.
 target/release/shacraft-compat import-anvil /path/to/java-world data/imported
 
+# Large playable maps: load compressed section baselines instead of block edit history.
+target/release/shacraft-compat import-anvil /path/to/java-world data/imported-large --baseline
+
 # Open the import in the browser through the server; select main in the world list.
 target/release/shacraft-server --data data/imported --listen 127.0.0.1:4000
 
@@ -34,6 +37,8 @@ target/release/shacraft-compat export-schem data artifacts/build --world lobby -
 
 The CLI prints a JSON report to stdout; errors produce JSON on stderr and a nonzero exit code. Conversion runs offline: `WorldStore` holds the same single-writer lock as the server, preventing concurrent edits from mixing revisions within one export. The source Java world must itself be a copy of a stopped world: changes to file size/timestamps during copying are detected, but this does not replace a consistent backup of a running Minecraft instance.
 
+`import-anvil --baseline` keeps the original source and conversion checks, but stores each nonempty section directly as the immutable world baseline. It avoids creating an undo record for every imported block. Imported revisions start at zero; later edits use the normal journal, and reset restores the imported map. Snapshots include the baseline. Unchanged exact exports and edited best-effort exports remain supported. Without this flag, the existing import behavior is unchanged.
+
 ## Implemented features
 
 - Big-endian NBT: all 12 payload types, numeric widths, float/double bit patterns, signed arrays, Java modified UTF-8/CESU-8, Unicode, the element type of an empty list, and unknown compound fields. Duplicate compound keys, impossible lengths, excessive depth, and trailing decompressed bytes are rejected.