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/common/kigi-tool-protocol/src/connection.rs

@@ -2,8 +2,8 @@
 
 use serde::{Deserialize, Serialize};
 
-/// Role of a WebSocket connection. The computer hub uses this to decide
-/// which methods are valid on a given socket.
+/// Role of a WebSocket connection; the computer hub decides from it which
+/// methods are valid on a given socket.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
 #[serde(rename_all = "snake_case")]
 pub enum ConnectionKind {
@@ -13,9 +13,6 @@ pub enum ConnectionKind {
 
 /// How the computer hub exposes the registered tool set to the model.
 ///
-/// `Concise` carries a configurable meta-tool pair so callers can choose
-/// the model-facing names of the search/invoke meta-tools per session.
-///
 /// Wire form is adjacently tagged on `mode`: `Full` serialises as
 /// `{"mode": "full"}` (an object, not a bare string), and `Concise` as
 /// `{"mode": "concise", "meta_search": "...", "meta_call": "..."}`.