fix(cubeai): add Default impl for CubeAi to satisfy clippy -D warnings

clippy flagged "you should consider adding a `Default` implementation for
`CubeAi`". Add the impl delegating to `new()`.

Also: impl block methods had been accidentally pulled out of `impl CubeAi`
into module scope during a prior edit; rewrite the impl block with all
methods (ingest_trace, classify, suggest, ingest_and_suggest, store)
inside it so it compiles.

Verification: all 5 cubeai tests pass, clippy clean.

Co-Authored-By: Hermes Agent

cubeai/src/lib.rs

@@ -182,9 +182,6 @@ impl CubeAi {
         let mut out = Vec::new();
         match kind {
             BlockKind::Computation => {
-                // Suggest vectorizing a repeated multiply-by-constant:
-                // Mul(const) -> Const(shift?), but keep it conservative:
-                // replace Mul with a left-shift when operand is a power of two.
                 out.push(Suggestion {
                     rule: TranslationRule {
                         name: format!("compute-opt:{:?}", block.label),
@@ -240,6 +237,12 @@ impl CubeAi {
     }
 }
 
+impl Default for CubeAi {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;