docs(skills): add build style skill

.pi/prompts/review.md

@@ -10,8 +10,8 @@ Choose skills from the reviewed files:
 
 - Use the `nix-style` skill for `*.nix` files.
 - Use the `rust-style` skill for `*.rs` files.
-- Use the `rust-style` skill for `Cargo.toml` files.
-- Use the `rust-style` skill for Bazel files that define Rust targets.
+- Use the `build-style` skill for `Cargo.toml` files.
+- Use the `build-style` skill for Bazel `BUILD` files.
 
 If the target includes multiple matching file types, use all matching skills.
 If the target is a diff, choose skills from the changed files.
@@ -35,7 +35,7 @@ Fix: suggested fix
 Keep the code excerpt to one to three lines when possible.
 Use a longer excerpt only when the violation needs surrounding context.
 Use `...` to omit unrelated lines from a multi-line excerpt.
-Use a style-skill rule citation, such as `rust::files.md:23` or `nix::let.md:7`.
+Use a style-skill rule citation in the form `skill::rule-file:line`.
 Make the fix direct.
 Do not include alternatives when one fix best follows the cited rule.
 

.pi/skills/build-style

@@ -0,0 +1 @@
+../../src/skills/style/build