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-system-power/src/lib.rs

@@ -7,7 +7,7 @@
 //! token and the user is forced to re-login. See
 //! `kigi-shell`'s `AuthManager` sleep gate, which consumes these events to
 //! avoid *starting* a refresh just before sleep. An in-flight refresh is
-//! deliberately left to finish, never aborted (dropping it could discard a
+//! Deliberately left to finish, never aborted (dropping it could discard a
 //! rotated-token response and cause the very revocation this guards against);
 //! instead, its [`PowerEvent::WillSleep`] handler may block briefly (bounded)
 //! to hold off the suspend until that in-flight refresh completes — see the
@@ -49,7 +49,7 @@ pub enum PowerEvent {
     /// Handlers must therefore be idempotent and safe to "cancel" via
     /// `DidWake`.
     WillSleep,
-    /// The system resumed from sleep, or a previously announced sleep was
+    /// The system resumed from sleep, or a earlier announced sleep was
     /// cancelled (macOS `kIOMessageSystemWillNotSleep` after a vetoed
     /// idle-sleep query). Both mean "not sleeping (anymore)".
     DidWake,
@@ -161,7 +161,7 @@ mod tests {
     #[test]
     fn power_event_is_copy_eq() {
         let e = PowerEvent::WillSleep;
-        let copied = e; // Copy
+        let copied = e;
         assert_eq!(e, copied);
         assert_ne!(PowerEvent::WillSleep, PowerEvent::DidWake);
     }