feat(frontend): prerender canonical URL for subpages

package.json

@@ -14,10 +14,11 @@
 		"build:compress": "./scripts/build.compress.sh",
 		"build:csp": "node scripts/build.csp.mjs",
 		"build:metadata": "node scripts/build.metadata.mjs",
+		"build:seo": "node scripts/build.seo.mjs",
 		"build:style": "node scripts/build.style.mjs",
 		"build:ic-domains": "node scripts/build.ic-domains.mjs",
 		"build:ii-alternative-origins": "node scripts/build.ii-alternative-origins.mjs",
-		"build:post-process": "npm run build:style && npm run build:metadata && npm run build:ic-domains && npm run build:ii-alternative-origins && npm run build:csp && npm run build:compress",
+		"build:post-process": "npm run build:style && npm run build:metadata && npm run build:seo && npm run build:ic-domains && npm run build:ii-alternative-origins && npm run build:csp && npm run build:compress",
 		"build:tokens-sns": "vite-node scripts/build.tokens.sns.ts && npm run format:file --file=src/frontend/src/env/tokens/tokens.sns.json",
 		"build:tokens-ckerc20": "vite-node scripts/build.tokens.ckerc20.ts && npm run format:file --file=src/frontend/src/env/tokens/tokens.ckerc20.json",
 		"build:tokens-icrc": "vite-node scripts/build.tokens.icrc.ts && npm run format:file --file=src/frontend/src/env/tokens/tokens.icrc.json",

scripts/build.seo.mjs

@@ -0,0 +1,38 @@
+import { readFileSync, writeFileSync } from 'node:fs';
+import { dirname, join, relative } from 'node:path';
+import { ENV, OISY_IC_DOMAIN, findHtmlFiles } from './build.utils.mjs';
+
+const OUTPUT_DIR = join(process.cwd(), 'build');
+const SITE_ROOT_CANONICAL = ENV !== 'production' ? OISY_IC_DOMAIN : 'https://oisy.com';
+
+const updateCanonical = (htmlFilePath) => {
+	// 1. We determine the route based on the output
+	const routePath = dirname(relative(OUTPUT_DIR, htmlFilePath));
+
+	// 2. Build the effective canonical route
+	const canonicalPath = `${SITE_ROOT_CANONICAL}/${routePath}/`;
+
+	// 2. Read content
+	let html = readFileSync(htmlFilePath, 'utf-8');
+
+	// 3. Update canonical
+	html = html.replace(
+		`<link href="${SITE_ROOT_CANONICAL}" rel="canonical" />`,
+		`<link href="${canonicalPath}" rel="canonical" />`
+	);
+
+	// 4. Update og:url to reflect the canonical
+	html = html.replace(
+		`<meta content="${SITE_ROOT_CANONICAL}" property="og:url" />`,
+		`<meta content="${canonicalPath}" property="og:url" />`
+	);
+
+	// 5. Save the content with the updated canonical URL
+	writeFileSync(htmlFilePath, html);
+};
+
+// Do not replace canonical for root and 404 pages
+const filterSubPages = (htmlFile) => dirname(htmlFile) !== OUTPUT_DIR;
+
+const htmlFiles = findHtmlFiles().filter(filterSubPages);
+htmlFiles.forEach((htmlFile) => updateCanonical(htmlFile));