feat(skills): add Rust file naming rules

src/skills/style/rust/rules/bazel.md

@@ -1,16 +1,5 @@
 # Bazel rules
 
-## Keep Rust tests in separate files
-
-### Rule
-
-Put Rust tests in separate `*_test.rs` files.
-Do not add inline `#[cfg(test)]` modules.
-
-### Rationale
-
-Separate test files keep production modules focused and match the repository's Bazel test layout.
-
 ## Declare Rust tests in Bazel
 
 ### Rule

src/skills/style/rust/rules/files.md

@@ -0,0 +1,26 @@
+# File rules
+
+## Avoid generic Rust file names
+
+### Rule
+
+Do not name Rust source files `lib.rs` or `main.rs`.
+Name library crate root files after the crate they define.
+Name binary crate root files after the binary they define, or use a `_main.rs` suffix.
+Set explicit Cargo paths and Bazel `srcs` when needed.
+
+### Rationale
+
+Generic root names make file search results and review context less clear.
+Descriptive file names show which crate or binary owns the code.
+
+## Keep Rust tests in separate files
+
+### Rule
+
+Put Rust tests in separate `*_test.rs` files.
+Do not add inline `#[cfg(test)]` modules.
+
+### Rationale
+
+Separate test files keep production modules focused and match the repository's Bazel test layout.