Fix v4l2loopback exclusive_caps, YU12->NV21 conversion, cameraserver crash

- Add exclusive_caps=0 to v4l2loopback insmod params to allow multiple
  simultaneous readers (HAL + verification capture)
- Fix YU12->NV21 pixel format conversion in V4L2 reader thread
- Fix YUYV->NV21 conversion as well
- Fix cameraserver crash by setting inputBuffer.streamId = -1
- Enable Hal Buffer Manager for requestStreamBuffers support
- Add JPEG_MAX_SIZE and JPEG_AVAILABLE_THUMBNAIL_SIZES metadata
- Add availableRequestKeys and availableResultKeys metadata
- Fix consumerUsage=0 for output streams (Camera3Device requirement)
- Fix metadata buffer overflow (2048->4096 bytes)

webroot/script.js

@@ -0,0 +1,69 @@
+const CMD='/data/adb/modules/virtualcam/control.sh';
+function log(m,t){const e=document.getElementById('console');const d=new Date();
+  e.innerHTML+=`<div class="${t||'log'}">[${d.toLocaleTimeString()}] ${m}</div>`;e.scrollTop=e.scrollHeight}
+async function exec(c){try{return await KSU.exec(c)}catch(e){log('exec error','err');return null}}
+
+async function loadConfig(){
+  const r=await exec(CMD+' get_config');if(!r)return;
+  try{const c=JSON.parse(r);
+    document.querySelector(`.src-btn[data-src="${c.source_type}"]`).click();
+    document.getElementById('rtsp-url').value=c.rtsp_url||'';
+    document.getElementById('mp4-path').value=c.mp4_path||'';
+    document.getElementById('res-w').value=c.res_w||1920;
+    document.getElementById('res-h').value=c.res_h||1080;
+    document.getElementById('fps').value=c.fps||30;
+  }catch(e){}
+}
+
+async function status(){
+  const r=await exec(CMD+' status');if(!r)return;
+  try{
+    const s=JSON.parse(r);const d=document.getElementById('status-dash');
+    const items=[['Provider',s.provider_pid>0?'green':'red',s.provider_pid>0?'Running':'Stopped'],
+      ['Feeder',s.feeder_pid>0?'green':'red',s.feeder_pid>0?'Running':'Stopped'],
+      ['Service',s.service_registered==1?'green':'red',s.service_registered==1?'Registered':'Not found'],
+      ['v4l2',s.v4l2_loaded==1?'green':'red',s.v4l2_loaded==1?'Loaded':'Missing'],
+      ['Device','yellow',s.video0||'N/A']];
+    d.innerHTML=items.map(i=>`<div class="stat"><span class="l">${i[0]}</span><span class="v ${i[1]}">${i[2]}</span></div>`).join('');
+    log('Status updated','ok');
+  }catch(e){log('Parse error','err')}
+}
+
+document.addEventListener('DOMContentLoaded',()=>{
+  loadConfig();
+  status();
+  document.querySelectorAll('.src-btn').forEach(b=>{
+    b.addEventListener('click',()=>{
+      document.querySelectorAll('.src-btn').forEach(x=>x.classList.remove('active'));
+      b.classList.add('active');
+      document.getElementById('rtsp-config').classList.toggle('hidden',b.dataset.src!=='rtsp');
+      document.getElementById('mp4-config').classList.toggle('hidden',b.dataset.src!=='mp4');
+    });
+  });
+  document.getElementById('btn-save').addEventListener('click',async()=>{
+    const src=document.querySelector('.src-btn.active').dataset.src;
+    const rtsp=document.getElementById('rtsp-url').value;
+    const mp4=document.getElementById('mp4-path').value;
+    const w=document.getElementById('res-w').value||1920;
+    const h=document.getElementById('res-h').value||1080;
+    const f=document.getElementById('fps').value||30;
+    await exec(`echo '{"source_type":"${src}","rtsp_url":"${rtsp}","mp4_path":"${mp4}","res_w":${w},"res_h":${h},"fps":${f}}' > /data/local/tmp/virtualcam_config.json`);
+    log('Config saved','ok');
+  });
+  document.getElementById('btn-start').addEventListener('click',async()=>{
+    log('Starting provider...','info');await exec(CMD+' start');log('Provider started','ok');setTimeout(status,3000);
+  });
+  document.getElementById('btn-stop').addEventListener('click',async()=>{
+    log('Stopping...','info');await exec(CMD+' stop');log('Stopped','ok');status();
+  });
+  document.getElementById('btn-restart').addEventListener('click',async()=>{
+    log('Restarting provider...','info');await exec(CMD+' restart');log('Provider restarted','ok');setTimeout(status,3000);
+  });
+  document.getElementById('btn-feed').addEventListener('click',async()=>{
+    log('Starting feeder...','info');await exec(CMD+' start_feeder');log('Feeder started','ok');setTimeout(status,2000);
+  });
+  document.getElementById('btn-unfeed').addEventListener('click',async()=>{
+    log('Stopping feeder...','info');await exec(CMD+' stop_feeder');log('Feeder stopped','ok');status();
+  });
+  document.getElementById('btn-refresh').addEventListener('click',status);
+});