refactor!: rename slhx to hemx

Rename the tracked product identity, crate/package names, Rust paths/macros, generated artifacts, runtime files, public attributes, examples, docs, requirements, and tests from slhx to hemx without compatibility shims.

Verified with cargo run -p hemx-xtask -- test, cargo test -p hemx-derive --test compile_fail, cargo test -p hemx-js, cargo test -p hemx-axum, cargo test -p hemx-v0-examples, cargo check --workspace, redgate list, redgate refs, redgate health --strict, git diff --check, and git grep/ls-files legacy-name audits.

req: misc/001

req: codegen/001

req: component/004

req: runtime/001

hemx-derive/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "hemx-derive"
+version.workspace = true
+edition.workspace = true
+
+[lib]
+proc-macro = true
+path = "src/lib.rs"
+
+[dependencies]
+proc-macro2 = "1"
+quote = "1"
+syn = { version = "2", features = ["full"] }