ci: make CI genuinely green — rust-ci toolchain pin + fmt/clippy (#43)

## Summary

Make CI genuinely green. The shared rust-ci pin on `main` predates
standards#439, so the SHA-pinned `dtolnay/rust-toolchain` step errors
out before the job runs. This bumps the pin so rust-ci actually runs,
and brings the Rust sources to fmt + clippy(`-D warnings`) clean under
the CI toolchain (stable 1.96).

## Changes

- **rust-ci:** bump `rust-ci-reusable.yml` pin `d135b05` → `8dc2bf0`
(current `standards` HEAD; includes #439 toolchain fix + #441/#442).
- **Rust hygiene:** `cargo fmt` + `clippy --fix` where the repo had
pre-existing drift, so `cargo fmt --all -- --check` and `cargo clippy
--locked --all-targets -- -D warnings` pass.

## RSR Quality Checklist

### Required
- [x] Tests pass (`cargo test --locked --all-targets`)
- [x] Code is formatted (`cargo fmt --all -- --check`)
- [x] Linter is clean (`cargo clippy --locked --all-targets -- -D
warnings`)
- [x] No banned language patterns
- [x] SPDX license headers present on modified files
- [x] No secrets, credentials, or `.env` files included

## Testing

Verified locally with the CI toolchain (rustc/clippy/rustfmt 1.96.0):
`cargo fmt --check`, `clippy -D warnings`, `cargo check --locked`,
`cargo test --locked` all pass.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---
_Generated by [Claude
Code](https://claude.ai/code/session_01A6PSzJWpRxtzGDjUCEh7Mx)_

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: hyperpolymath

.github/workflows/rust-ci.yml

@@ -14,4 +14,4 @@ permissions:
 
 jobs:
   rust-ci:
-    uses: hyperpolymath/standards/.github/workflows/rust-ci-reusable.yml@d135b05bfc647d0c0fbfedc7e80f37ea50f49236
+    uses: hyperpolymath/standards/.github/workflows/rust-ci-reusable.yml@8dc2bf039d1ff0372d650895c46bea7fbaec68ff

src/abi/mod.rs

@@ -506,8 +506,8 @@ mod tests {
 
     #[test]
     fn test_custom_distribution_valid() {
-        let d =
-            Distribution::new_custom("mixture(0.5, normal(0,1), normal(5,2))".to_string()).expect("TODO: handle error");
+        let d = Distribution::new_custom("mixture(0.5, normal(0,1), normal(5,2))".to_string())
+            .expect("TODO: handle error");
         assert_eq!(d.kind(), "custom");
     }
 

src/codegen/codegen.rs

@@ -63,7 +63,8 @@ fn emit_header(code: &mut String, project_name: &str) {
     writeln!(code, "// Project: {}", project_name).expect("TODO: handle error");
     writeln!(code, "// SPDX-License-Identifier: MPL-2.0").expect("TODO: handle error");
     writeln!(code).expect("TODO: handle error");
-    writeln!(code, "module {} where", sanitize_identifier(project_name)).expect("TODO: handle error");
+    writeln!(code, "module {} where", sanitize_identifier(project_name))
+        .expect("TODO: handle error");
     writeln!(code).expect("TODO: handle error");
 }
 
@@ -78,7 +79,8 @@ fn emit_distribution_declarations(code: &mut String, variables: &[ParsedVariable
         let btype = betlang_type(&var.distribution);
 
         writeln!(code, "/// {} — {}", var.name, info.description).expect("TODO: handle error");
-        writeln!(code, "/// Sampling method: {}", info.sampling_method).expect("TODO: handle error");
+        writeln!(code, "/// Sampling method: {}", info.sampling_method)
+            .expect("TODO: handle error");
         writeln!(code, "/// Support: {}", info.support).expect("TODO: handle error");
         writeln!(
             code,
@@ -113,15 +115,17 @@ fn emit_ternary_helpers(code: &mut String, variables: &[ParsedVariable]) {
     writeln!(code).expect("TODO: handle error");
 
     writeln!(code, "/// Kleene strong three-valued AND").expect("TODO: handle error");
-    writeln!(code, "let ternary_and(a: Ternary, b: Ternary) -> Ternary =").expect("TODO: handle error");
+    writeln!(code, "let ternary_and(a: Ternary, b: Ternary) -> Ternary =")
+        .expect("TODO: handle error");
     writeln!(code, "  match (a, b) with").expect("TODO: handle error");
     writeln!(code, "  | (False, _) | (_, False) -> False").expect("TODO: handle error");
     writeln!(code, "  | (True, True)            -> True").expect("TODO: handle error");
     writeln!(code, "  | _                       -> Unknown").expect("TODO: handle error");
     writeln!(code).expect("TODO: handle error");
 
     writeln!(code, "/// Kleene strong three-valued OR").expect("TODO: handle error");
-    writeln!(code, "let ternary_or(a: Ternary, b: Ternary) -> Ternary =").expect("TODO: handle error");
+    writeln!(code, "let ternary_or(a: Ternary, b: Ternary) -> Ternary =")
+        .expect("TODO: handle error");
     writeln!(code, "  match (a, b) with").expect("TODO: handle error");
     writeln!(code, "  | (True, _) | (_, True)   -> True").expect("TODO: handle error");
     writeln!(code, "  | (False, False)           -> False").expect("TODO: handle error");
@@ -191,7 +195,8 @@ fn emit_entry_point(code: &mut String, variables: &[ParsedVariable], config: &Ab
     }
 
     writeln!(code, "  }}").expect("TODO: handle error");
-    writeln!(code, "  report(results, confidence={})", config.confidence).expect("TODO: handle error");
+    writeln!(code, "  report(results, confidence={})", config.confidence)
+        .expect("TODO: handle error");
 }
 
 /// Sanitize a project name into a valid Betlang module identifier.