docs(comments): rewrite comments across all crates to the guidelines

Sweep every first-party crate source (1956 .rs files) to the project comment
guidelines: delete redundant restatements, decorative banners, change
narration, and end-of-line comments; keep and tighten the crucial ones
(invariants, bug rationale, SAFETY blocks, ported-source attribution).

No functional code changed. Every edit is proven comment-only against the
prior tree by a comment-stripping lexer (string/char/raw-string aware) plus a
separate doctest-fence check. Where removing a comment made rustfmt or clippy
want to re-lay-out adjacent code, the minimal triggering comment is restored so
code tokens stay byte-identical.

Gates green: cargo fmt --all --check (0 diffs), cargo check and cargo clippy
--workspace --all-targets (0 warnings).

Adds scripts/check_codegen_comment_guidelines.py — the enforcement gate for
these guidelines (flags banners, end-of-line comments, change narration, and
commented-out code).

crates/codegen/kigi-shell/src/util/config/resolve/compaction.rs

@@ -134,9 +134,13 @@ mod compaction_wall_clock_budget_tests {
     // Assumes KIGI_COMPACTION_WALL_CLOCK_SECS is unset in the test env.
     #[test]
     fn default_global_disable_and_no_clamp() {
-        assert_eq!(resolve(None), 300); // client default
-        assert_eq!(resolve(Some(450)), 450); // server global wins
-        assert_eq!(resolve(Some(0)), 0); // 0 explicitly disables (no clamp)
-        assert_eq!(resolve(Some(5)), 5); // low values pass through (warned, not clamped)
+        // client default
+        assert_eq!(resolve(None), 300);
+        // server global wins
+        assert_eq!(resolve(Some(450)), 450);
+        // 0 explicitly disables (no clamp)
+        assert_eq!(resolve(Some(0)), 0);
+        // low values pass through (warned, not clamped)
+        assert_eq!(resolve(Some(5)), 5);
     }
 }