feat: parallelize check tasks with real-time progress output

Justfile

@@ -3,12 +3,67 @@ set dotenv-load
 default:
 	just --list
 
+[script("bun")]
 check:
-    bun run --cwd web format
-    bun run --cwd web lint
-    bun run --cwd web check
-    cargo clippy --all-targets
-    cargo fmt --check
+    const checks = [
+      { name: "prettier", cmd: ["bun", "run", "--cwd", "web", "format:check"] },
+      { name: "eslint", cmd: ["bun", "run", "--cwd", "web", "lint"] },
+      { name: "svelte-check", cmd: ["bun", "run", "--cwd", "web", "check"] },
+      { name: "clippy", cmd: ["cargo", "clippy", "--all-targets"] },
+      { name: "rustfmt", cmd: ["cargo", "fmt", "--check"] },
+    ];
+
+    const start = Date.now();
+    const remaining = new Set(checks.map(c => c.name));
+    const results = [];
+
+    // Spawn all checks in parallel
+    const promises = checks.map(async (check) => {
+      const proc = Bun.spawn(check.cmd, {
+        env: { ...process.env, FORCE_COLOR: "1" },
+        stdout: "pipe",
+        stderr: "pipe",
+      });
+
+      const [stdout, stderr] = await Promise.all([
+        new Response(proc.stdout).text(),
+        new Response(proc.stderr).text(),
+      ]);
+
+      await proc.exited;
+      const elapsed = ((Date.now() - start) / 1000).toFixed(1);
+      
+      return { ...check, stdout, stderr, exitCode: proc.exitCode, elapsed };
+    });
+
+    // Progress updater
+    const interval = setInterval(() => {
+      const elapsed = ((Date.now() - start) / 1000).toFixed(1);
+      const tasks = Array.from(remaining).join(", ");
+      process.stderr.write(`\r\x1b[K${elapsed}s [${tasks}]`);
+    }, 100);
+
+    // Stream outputs as they complete
+    let anyFailed = false;
+    for (const promise of promises) {
+      const result = await promise;
+      remaining.delete(result.name);
+
+      if (result.exitCode !== 0) {
+        anyFailed = true;
+        process.stderr.write(`\r\x1b[K`);
+        process.stdout.write(`❌ ${result.name} (${result.elapsed}s)\n`);
+        if (result.stdout) process.stdout.write(result.stdout);
+        if (result.stderr) process.stderr.write(result.stderr);
+      } else {
+        process.stderr.write(`\r\x1b[K`);
+        process.stdout.write(`✅ ${result.name} (${result.elapsed}s)\n`);
+      }
+    }
+
+    clearInterval(interval);
+    process.stderr.write(`\r\x1b[K`);
+    process.exit(anyFailed ? 1 : 0);
 
 build:
     bun run --cwd web build