test(guards): strip comments the way the compiler reads them, in every guard

Forty-two guard files carried their own comment stripper, block comments
first in one non-greedy pass, so a /* inside a line comment opened a
block that hid the code after it, and the stricter copies hid code
behind a /* inside a string, which every e2e route glob has. They all
read through the shared stripComments now, and it scans the way the
parser does: strings, template literals and regular expressions keep
every character, a comment inside a template expression goes, and line
numbers are kept. A parity test strips every source file both ways,
with the scanner and with the TypeScript parser, and fails on the first
that differs.

No guard reports anything new. Each one fails when the stripper returns
nothing; three of them passed on an empty file and assert that the code
they ban is read at all now.

src/components/day/__tests__/day-door-coverage-guard.test.ts

@@ -2,6 +2,7 @@ import { readdirSync, readFileSync, statSync } from "node:fs";
 import { join, relative } from "node:path";
 
 import { describe, expect, it } from "vitest";
+import { stripComments } from "../../../__tests__/helpers/source-files";
 
 /**
  * Every chart drawn in days is a door to its days, or it says why not.
@@ -120,17 +121,6 @@ function walk(path: string): string[] {
 
 const files = SCAN.flatMap(walk).filter((f) => /\.tsx?$/.test(f));
 const rel = (abs: string) => relative(ROOT, abs);
-/**
- * The code without its comments: a docblock that names `<HealthChart>` is
- * not a mount. Block comments (JSX ones included) go whole; a line comment
- * goes from `//` to the line end unless the slashes follow a colon (a URL).
- */
-export function stripComments(text: string): string {
-  return text
-    .replace(/\/\*[\s\S]*?\*\//g, "")
-    .replace(/(^|[^:"'`])\/\/.*$/gm, "$1");
-}
-
 const read = new Map(
   files.map((f) => [rel(f), stripComments(readFileSync(f, "utf8"))]),
 );