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/src/context.rs

@@ -0,0 +1,13 @@
+//! Invocation context passed to a module on every call.
+//!
+//! Mirrors the WIT `invocation-context` record. The
+//! `#[fai_module]` macro builds this from the WIT-generated value
+//! before handing it to user code.
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Context {
+    pub invocation_id: String,
+    pub capability_namespace: String,
+    pub capability_name: String,
+    pub deadline_ms: u64,
+}