fix: live journal camera save on Android

Use native camera picker on mobile, add preview-and-save step, and
harden canvas capture with toDataURL fallback when toBlob fails.

Co-authored-by: Cursor <cursoragent@cursor.com>

client/src/utils/captureVideoFrame.ts

@@ -0,0 +1,59 @@
+/** Capture current video frame as JPEG blob (with Android-safe fallbacks). */
+export async function captureVideoFrame(video: HTMLVideoElement, quality = 0.92): Promise<Blob> {
+  const width = video.videoWidth
+  const height = video.videoHeight
+  if (!width || !height) {
+    throw new Error('video_frame_not_ready')
+  }
+
+  const canvas = document.createElement('canvas')
+  canvas.width = width
+  canvas.height = height
+  const ctx = canvas.getContext('2d')
+  if (!ctx) {
+    throw new Error('canvas_context_unavailable')
+  }
+  ctx.drawImage(video, 0, 0, width, height)
+
+  const blob = await canvasToJpegBlob(canvas, quality)
+  if (blob) return blob
+
+  const dataUrl = canvas.toDataURL('image/jpeg', quality)
+  const response = await fetch(dataUrl)
+  const fallback = await response.blob()
+  if (!fallback.size) {
+    throw new Error('capture_encode_failed')
+  }
+  return fallback
+}
+
+function canvasToJpegBlob(canvas: HTMLCanvasElement, quality: number): Promise<Blob | null> {
+  return new Promise((resolve) => {
+    let settled = false
+    const finish = (blob: Blob | null) => {
+      if (settled) return
+      settled = true
+      window.clearTimeout(timer)
+      resolve(blob)
+    }
+
+    const timer = window.setTimeout(() => finish(null), 3000)
+
+    try {
+      canvas.toBlob((blob) => finish(blob), 'image/jpeg', quality)
+    } catch {
+      finish(null)
+    }
+  })
+}
+
+/** Mobile: native camera via file input is more reliable than getUserMedia + canvas. */
+export function preferNativeCameraPicker(): boolean {
+  if (typeof window === 'undefined') return false
+  const ua = navigator.userAgent
+  if (/Android|iPhone|iPad|iPod/i.test(ua)) return true
+  const touch = 'ontouchstart' in window || navigator.maxTouchPoints > 0
+  const coarse = window.matchMedia('(pointer: coarse)').matches
+  const narrow = window.matchMedia('(max-width: 768px)').matches
+  return touch && (coarse || narrow)
+}