fix: remove workspace exclude, add [lib] to burn crate

- Remove burn from exclude list — all crates now in workspace
- Add [lib] section to burn Cargo.toml (edition 2024 requires explicit target)
- p64: 23 tests pass, phyllotactic-manifold: 14 tests pass
- Full workspace compiles clean

https://claude.ai/code/session_01BTATTRUACijvsK4hqmKUBR

Author: claude

Cargo.toml

@@ -105,11 +105,7 @@ members = [
     "ndarray-rand",
     "crates/*",
 ]
-exclude = [
-    # burn crate requires edition 2024 (Rust 1.85+) and pinned git deps.
-    # Built separately: cargo check --manifest-path crates/burn/Cargo.toml
-    "crates/burn",
-]
+exclude = []
 default-members = [
     ".",
     "ndarray-rand",

crates/burn/Cargo.toml

@@ -11,6 +11,10 @@ Goal: replace macerator SIMD with crate::simd F32x16 + LazyLock dispatch,
 add bgz-tensor AttentionTable compiled attention path.
 """
 
+[lib]
+name = "burn_ndarray"
+path = "src/lib.rs"
+
 [features]
 default = ["std", "simd", "multi-threads"]
 multi-threads = ["rayon", "ndarray/rayon", "matrixmultiply/threading"]