refactor: rename crate fai-module-sdk -> chain-module-sdk

The SDK is product-scoped (Ch∆In's module SDK), not a generic vendor
crate — a future Brain SDK would collide. Crate + macros renamed to
chain-module-sdk[-macros]; repo + dir follow.

Signed-off-by: flemming-it <sf@flemming.it>

crates/chain-module-sdk/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "chain-module-sdk"
+version.workspace = true
+edition.workspace = true
+authors.workspace = true
+license.workspace = true
+repository.workspace = true
+homepage.workspace = true
+rust-version.workspace = true
+description = "Stable, ergonomic surface for writing Ch∆In modules in Rust"
+
+[dependencies]
+chain-module-sdk-macros = { path = "../chain-module-sdk-macros" }
+serde = { workspace = true }
+serde_json = { workspace = true }
+thiserror = { workspace = true }
+wit-bindgen = { workspace = true }
+
+[dev-dependencies]
+sha2 = { workspace = true }
+
+[lints]
+workspace = true