ci(format): enforce stable rustfmt + drop continue-on-error band-aid

PR #133 (commits 7ca1cf3 + ed59b3b) stripped all 13 nightly-only
directives from `rustfmt.toml` and normalized the codebase to stable
rustfmt 1.94.1. The CI fmt job, however, was never updated to leverage
this — it still used:

  uses: dtolnay/rust-toolchain@nightly
  continue-on-error: true

…which left fmt failures showing as "passing" on PR checks (an
atom-bomb red flag for code-style invariants). The original
`continue-on-error: true` rationale ("5,679 drift sites with nightly
rustfmt") was dependent on the nightly-only directives that PR #133
already removed. The band-aid was stale.

This commit completes what PR #133 implied:

- Switch fmt job from `dtolnay/rust-toolchain@nightly` to
  `dtolnay/rust-toolchain@1.95.0` (the rust-toolchain.toml pin).
- Remove `continue-on-error: true` — fmt failures now block merge,
  as they should.
- Rename the job from `format/nightly` → `format/stable` to reflect
  the actual toolchain.
- Replace the stale 24-line comment block with a 12-line explanation
  citing PR #133 as the source of stable-clean state.

Plus the 3 drift sites between stable 1.94.1 and stable 1.95.0
(import ordering changes in `src/hpc/clam.rs`, `src/hpc/mod.rs`,
`src/hpc/udf_kernels.rs`) — `cargo fmt --all` on 1.95.0 normalizes
them. Bundled with the 1.95 bump since this PR is the trigger.

Verified: `cargo fmt --all --check` clean on 1.95.0 post-commit.

Companion to PR #133 / "where did that PR go" — completes the missed
step.

Author: claude

.github/workflows/ci.yaml

@@ -61,28 +61,23 @@ jobs:
 
   format:
     runs-on: ubuntu-latest
-    name: format/nightly
-    # Marked non-blocking until a separate fmt-sweep PR aligns the
-    # codebase with `rustfmt.toml`. Local audit (2026-04-30) under
-    # `cargo +nightly fmt --all -- --check` reports 5,679 drift sites —
-    # too large to bundle into a CI-fix PR. The format job remains in
-    # the pipeline as a continuous signal so the sweep author can verify
-    # zero drift after running `cargo +nightly fmt --all`, but it does
-    # not gate merge until that sweep lands.
-    continue-on-error: true
+    name: format/stable
+    # Blocking — no continue-on-error. `rustfmt.toml` was stripped of all
+    # nightly-only directives in PR #133 (`7ca1cf3d chore(fmt): strip
+    # unstable rustfmt options, keep stable-only config` + `ed59b3b1
+    # style: normalize codebase to stable rustfmt 1.94.1`) and the
+    # codebase normalized — so stable rustfmt enforces the project's
+    # style losslessly. The previous `continue-on-error: true` +
+    # `dtolnay/rust-toolchain@nightly` setup was a stale band-aid from
+    # when `brace_style = AlwaysNextLine`, `imports_granularity =
+    # Preserve`, `unstable_features = true` still lived in rustfmt.toml.
+    # That state no longer exists; the band-aid is removed in this PR.
     steps:
       - uses: actions/checkout@v4
-      # `rustfmt.toml` declares 13 nightly-only options
-      # (`brace_style = AlwaysNextLine`, `imports_granularity = Preserve`,
-      # `unstable_features = true`, etc.). Stable rustfmt warns and
-      # ignores them, then produces drift on every nightly-formatted
-      # file because its defaults differ from the unstable settings.
-      # The format job MUST use nightly rustfmt for the project's chosen
-      # style to be enforceable.
-      #
-      # The compile + clippy jobs stay on 1.95.0 (pinned in
-      # `rust-toolchain.toml`) — only this fmt job needs nightly.
-      - uses: dtolnay/rust-toolchain@nightly
+      # Stable rustfmt 1.95.0 — pinned in `rust-toolchain.toml`. No
+      # nightly dependency since rustfmt.toml is stable-clean post-PR
+      # #133.
+      - uses: dtolnay/rust-toolchain@1.95.0
         with:
           components: rustfmt
       - run: cargo fmt --all --check

src/hpc/clam.rs

@@ -1281,7 +1281,7 @@ impl ClamTree {
 
 use super::bf16_truth::{AwarenessState, PackedQualia};
 use super::causality::{causality_decompose, CausalityDecomposition, NarsTruthValue};
-use super::node::{Node, SPO, S__, _P_, __O};
+use super::node::{Node, _P_, __O, SPO, S__};
 use super::plane::Distance as PlaneDistance;
 
 /// A verified hit enriched with causal metadata from SPO decomposition.

src/hpc/mod.rs

@@ -247,7 +247,7 @@ mod e2e_tests {
     use super::causality::{causality_decompose, CausalityDirection};
     use super::clam::{knn_brute, ClamTree};
     use super::fingerprint::Fingerprint;
-    use super::node::{Node, SPO, S__, _P_, __O};
+    use super::node::{Node, _P_, __O, SPO, S__};
     use super::seal::Seal;
 
     #[test]

src/hpc/udf_kernels.rs

@@ -22,7 +22,7 @@ use super::bf16_truth::{bf16_hamming_scalar, BF16Weights};
 use super::bitwise::hamming_distance_raw;
 use super::cascade::Cascade;
 use super::causality::{causality_decompose, CausalityDirection};
-use super::node::{Node, SPO, S__, _P_, __O};
+use super::node::{Node, _P_, __O, SPO, S__};
 use super::plane::Truth;
 
 // ============================================================================