fitness: add ExerciseDB v2 scrape data, media, and ID mapping

Scrape scripts for ExerciseDB v2 API (scrape-exercises.ts,
download-exercise-media.ts), raw data for 200 exercises with
images/videos, and a 1:1 mapping from ExerciseDB IDs to internal
kebab-case slugs (exercisedb-map.ts). 23 exercises matched to
existing internal IDs, 177 new slugs generated.

scripts/download-exercise-media.ts

@@ -0,0 +1,117 @@
+/**
+ * Downloads all exercise images and videos from the ExerciseDB CDN.
+ *
+ * Run with: pnpm exec vite-node scripts/download-exercise-media.ts
+ *
+ * Reads: src/lib/data/exercisedb-raw.json
+ * Outputs: static/fitness/exercises/<exerciseId>/
+ *   - images: 360p.jpg, 480p.jpg, 720p.jpg, 1080p.jpg
+ *   - video: video.mp4
+ *
+ * Resumes automatically — skips files that already exist on disk.
+ */
+import { readFileSync, existsSync, mkdirSync, writeFileSync } from 'fs';
+import { resolve, extname } from 'path';
+
+const RAW_PATH = resolve('src/lib/data/exercisedb-raw.json');
+const OUT_DIR = resolve('static/fitness/exercises');
+const CONCURRENCY = 10;
+
+interface DownloadTask {
+	url: string;
+	dest: string;
+}
+
+function sleep(ms: number) {
+	return new Promise(r => setTimeout(r, ms));
+}
+
+async function download(url: string, dest: string, retries = 3): Promise<boolean> {
+	for (let attempt = 1; attempt <= retries; attempt++) {
+		try {
+			const res = await fetch(url);
+			if (!res.ok) throw new Error(`${res.status} ${res.statusText}`);
+			const buf = Buffer.from(await res.arrayBuffer());
+			writeFileSync(dest, buf);
+			return true;
+		} catch (err: any) {
+			if (attempt === retries) {
+				console.error(`  FAILED ${url}: ${err.message}`);
+				return false;
+			}
+			await sleep(1000 * attempt);
+		}
+	}
+	return false;
+}
+
+async function runQueue(tasks: DownloadTask[]) {
+	let done = 0;
+	let failed = 0;
+	const total = tasks.length;
+
+	async function worker() {
+		while (tasks.length > 0) {
+			const task = tasks.shift()!;
+			const ok = await download(task.url, task.dest);
+			if (!ok) failed++;
+			done++;
+			if (done % 50 === 0 || done === total) {
+				console.log(`  ${done}/${total} downloaded${failed ? ` (${failed} failed)` : ''}`);
+			}
+		}
+	}
+
+	const workers = Array.from({ length: CONCURRENCY }, () => worker());
+	await Promise.all(workers);
+	return { done, failed };
+}
+
+async function main() {
+	console.log('=== Exercise Media Downloader ===\n');
+
+	if (!existsSync(RAW_PATH)) {
+		console.error(`Missing ${RAW_PATH} — run scrape-exercises.ts first`);
+		process.exit(1);
+	}
+
+	const data = JSON.parse(readFileSync(RAW_PATH, 'utf-8'));
+	const exercises: any[] = data.exercises;
+	console.log(`${exercises.length} exercises in raw data\n`);
+
+	const tasks: DownloadTask[] = [];
+
+	for (const ex of exercises) {
+		const dir = resolve(OUT_DIR, ex.exerciseId);
+		mkdirSync(dir, { recursive: true });
+
+		// Multi-resolution images
+		if (ex.imageUrls) {
+			for (const [res, url] of Object.entries(ex.imageUrls as Record<string, string>)) {
+				const ext = extname(new URL(url).pathname) || '.jpg';
+				const dest = resolve(dir, `${res}${ext}`);
+				if (!existsSync(dest)) tasks.push({ url, dest });
+			}
+		}
+
+		// Video
+		if (ex.videoUrl) {
+			const dest = resolve(dir, 'video.mp4');
+			if (!existsSync(dest)) tasks.push({ url: ex.videoUrl, dest });
+		}
+	}
+
+	if (tasks.length === 0) {
+		console.log('All media already downloaded!');
+		return;
+	}
+
+	console.log(`${tasks.length} files to download (skipping existing)\n`);
+	const { done, failed } = await runQueue(tasks);
+	console.log(`\nDone! ${done - failed} downloaded, ${failed} failed.`);
+}
+
+main().catch(err => {
+	console.error(err);
+	process.exit(1);
+});