Adds crates/headroom-core/src/transforms/code_compressor.rs (1,882 lines): the
AST-aware CodeCompressor ported to Rust on tree-sitter, with grammars for
Python, JavaScript, TypeScript, Go, Rust, Java, C and C++.
Parity-only, like #1153. Nothing calls it: the only references outside the
module are the pub mod / pub use declarations in transforms/mod.rs, and
live_zone.rs still routes SourceCode to a no-op. The pyo3 bridge is untouched
and no Python source changes, so the engine is unreachable from the shipped
package. #1155 wires it into live-zone dispatch.
Every grammar is pinned with '=' to the exact version of the corresponding
Python tree-sitter-<lang> PyPI wheel. Same version on crates.io and PyPI means
the same grammar.js, hence the same generated parser.c, hence node-for-node
identical ASTs — the precondition for byte-parity. A canary over 9 samples x 8
languages confirmed identical node-type and line-span trees at these pins;
bumping any pin requires re-running it and re-recording the fixtures.
Ships 30 recorded parity fixtures, a CodeCompressorComparator in
headroom-parity, and scripts/record_code_compressor_fixtures.py.
Verified byte-identical to the recorded Python output:
[code_aware_compressor] total=30 matched=30 skipped=0 diffed=0
Full harness on the merge result: 227 fixtures, 182 matched, 45 skipped
(cache_aligner + ccr stubs), 0 diffed, exit 0 — with kompress at 21/21 under
ONNX Runtime 1.24.4 (see #2591).
Also verified cargo check -p headroom-core --no-default-features passes, so the
static-musl path stays intact.
