feat(sdk): rename attribute to #[chain_module], keep #[fai_module] alias

The public macro name was the last product-scoped 'fai' identifier
in the SDK surface. #[chain_module] is now the primary attribute
(README + examples updated); #[fai_module] stays as a delegating
alias so modules written before the rename keep compiling. 0.2.1.

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

crates/chain-module-sdk/src/lib.rs

@@ -5,7 +5,7 @@
 //! ```ignore
 //! use chain_module_sdk::prelude::*;
 //!
-//! #[fai_module]
+//! #[chain_module]
 //! fn invoke(_ctx: Context, inputs: Inputs) -> Result<Outputs, ModuleError> {
 //!     let text = inputs.require_text("input")?;
 //!     Ok(Outputs::new().with_text("output", format!("got: {text}")))
@@ -36,9 +36,9 @@ pub use inputs::Inputs;
 pub use outputs::Outputs;
 pub use payload::{BytesValue, FileRef, Payload};
 
-pub use chain_module_sdk_macros::fai_module;
+pub use chain_module_sdk_macros::{chain_module, fai_module};
 
-// Emit-hook plumbing used by the `#[fai_module]` expansion (wasm32)
+// Emit-hook plumbing used by the `#[chain_module]` expansion (wasm32)
 // so `Context::emit` reaches the WIT `emit-event` host import.
 #[doc(hidden)]
 pub use host::__set_emit_hook;
@@ -48,11 +48,12 @@ pub(crate) use host::emit;
 /// every type a typical module needs into scope.
 pub mod prelude {
     pub use super::{
-        BytesValue, Context, FileRef, Inputs, ModuleError, Outputs, Payload, fai_module,
+        BytesValue, Context, FileRef, Inputs, ModuleError, Outputs, Payload, chain_module,
+        fai_module,
     };
 }
 
-/// Internal re-exports the `#[fai_module]` macro expansion depends on.
+/// Internal re-exports the `#[chain_module]` macro expansion depends on.
 ///
 /// Not part of the public API. Anything in this module may change
 /// between SDK patch releases.