feat: integrate Tailwind CSS for improved styling and layout

- Added Tailwind CSS and its Vite plugin to the frontend project.
- Updated App.svelte to enhance UI with Tailwind classes, including a new layout for the serial monitor and command tester.
- Improved logging functionality by increasing log history and adding more detailed log messages.
- Refactored SendBox.svelte for consistent styling with Tailwind.
- Enhanced Pico firmware to support structured event logging and command parsing.
- Updated README_PICO_SERIAL.md to provide comprehensive documentation on serial communication and backend integration.
- Added .dockerignore to optimize Docker builds by excluding unnecessary files.

backend/src/main.ts

@@ -1,8 +1,29 @@
 import { NestFactory } from '@nestjs/core';
 import { AppModule } from './app.module';
+import { NestExpressApplication } from '@nestjs/platform-express';
+import { join } from 'path';
 
 async function bootstrap() {
-  const app = await NestFactory.create(AppModule);
-  await app.listen(process.env.PORT ?? 3000);
+  const app = await NestFactory.create<NestExpressApplication>(AppModule, {
+    bufferLogs: true,
+  });
+
+  // Serve static frontend (built assets copied to /app/public in container)
+  const publicDir = join(process.cwd(), 'public');
+  app.useStaticAssets(publicDir);
+
+  // Basic health endpoint
+  app.getHttpAdapter().get('/healthz', (_req: any, res: any) => {
+    res.json({ ok: true, ts: Date.now() });
+  });
+
+  const port = Number(process.env.PORT || 3000);
+  await app.listen(port);
+  // eslint-disable-next-line no-console
+  console.log(`[bootstrap] Listening on :${port}`);
 }
-bootstrap();
+bootstrap().catch((e) => {
+  // eslint-disable-next-line no-console
+  console.error('Fatal bootstrap error', e);
+  process.exit(1);
+});

backend/src/serial/serial.service.ts

@@ -139,16 +139,44 @@ export class SerialService implements OnModuleDestroy, OnModuleInit {
     this.close();
   }
 
-  onModuleInit() {
-    const port = process.env.SERIAL_PORT;
-    const baud = process.env.SERIAL_BAUD ? Number(process.env.SERIAL_BAUD) : undefined;
-    if (port) {
+  async onModuleInit() {
+    // Priority: explicit env vars > auto-detect
+    const explicit = process.env.SERIAL_PORT || process.env.PICO_SERIAL_PORT;
+    const baud = Number(process.env.SERIAL_BAUD || process.env.PICO_BAUD || 115200);
+    if (explicit) {
       try {
-        console.log('[SerialService] AUTO opening port from SERIAL_PORT=', port, 'baud=', baud ?? 115200);
-        this.open(port, baud ?? 115200);
+        console.log('[SerialService] AUTO opening explicit port', explicit, 'baud=', baud);
+        this.open(explicit, baud);
+        return;
       } catch (e: any) {
-        console.warn('[SerialService] AUTO open failed', e?.message ?? e);
+        console.warn('[SerialService] explicit open failed', e?.message ?? e);
       }
     }
+
+    // Attempt auto-detect of Pico (USB first, then common UART paths)
+    try {
+      const ports = await this.listPorts();
+      // Prefer vendorId 2e8a (Pico)
+      let candidate = ports.find(p => (p.vendorId || '').toLowerCase() === '2e8a');
+      if (!candidate) {
+        const common = ['/dev/serial0', '/dev/ttyACM0', '/dev/ttyAMA0'];
+        candidate = ports.find(p => p.path && common.includes(p.path));
+      }
+      // Windows fallback: highest numbered COM port
+      if (!candidate) {
+        const winCom = ports
+          .filter(p => /^COM\d+$/i.test(p.path))
+          .sort((a, b) => Number(b.path.replace(/\D/g, '')) - Number(a.path.replace(/\D/g, '')))[0];
+        if (winCom) candidate = winCom;
+      }
+      if (candidate && candidate.path) {
+        console.log('[SerialService] AUTO opening detected port', candidate.path);
+        this.open(candidate.path, baud);
+      } else {
+        console.log('[SerialService] No serial port auto-detected (will remain idle)');
+      }
+    } catch (e: any) {
+      console.warn('[SerialService] auto-detect failed', e?.message ?? e);
+    }
   }
 }