Add upload from photo library button on capture screen

Adds an "Upload from Library" button below the camera button
that opens the device photo picker (no capture attribute) with
multi-select support. Selected photos are converted to JPEG and
queued for upload, with a progress counter during processing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/templates/capture.html

@@ -14,7 +14,11 @@
             📷 Take Photo
         </button>
 
-        <!-- Hidden file input as fallback -->
+        <button class="btn btn-secondary btn-upload" id="upload-btn">
+            🖼️ Upload from Library
+        </button>
+
+        <!-- Hidden file input as fallback for camera -->
         <input
             type="file"
             id="camera-input"
@@ -22,6 +26,15 @@
             capture="environment"
             style="display: none;"
         >
+
+        <!-- Hidden file input for photo library (multiple) -->
+        <input
+            type="file"
+            id="upload-input"
+            accept="image/*"
+            multiple
+            style="display: none;"
+        >
     </div>
 
     <div class="recent-photos" id="recent-photos">
@@ -98,6 +111,19 @@
     cursor: not-allowed;
 }
 
+.btn-upload {
+    font-size: 1.1rem;
+    padding: 1rem;
+    margin: 0.5rem 0;
+    background: var(--bg-secondary);
+    color: var(--text-primary);
+    border: 1px solid var(--bg-tertiary);
+}
+
+.btn-upload:disabled {
+    opacity: 0.6;
+}
+
 .recent-photos {
     margin-top: 3rem;
     padding-bottom: 2rem;
@@ -364,6 +390,43 @@ cameraInput.addEventListener('change', async function(e) {
     e.target.value = '';
 });
 
+// ---- Upload from library ----
+const uploadBtn = document.getElementById('upload-btn');
+const uploadInput = document.getElementById('upload-input');
+
+uploadBtn.addEventListener('click', function() {
+    uploadInput.click();
+});
+
+uploadInput.addEventListener('change', async function(e) {
+    const files = Array.from(e.target.files);
+    if (files.length === 0) return;
+
+    uploadBtn.disabled = true;
+    uploadBtn.textContent = '⏳ Processing 0/' + files.length + '...';
+
+    let saved = 0;
+    for (const file of files) {
+        try {
+            const jpegBlob = await convertToJPEG(file);
+            await savePhoto(jpegBlob);
+            saved++;
+            uploadBtn.textContent = '⏳ Processing ' + saved + '/' + files.length + '...';
+        } catch (err) {
+            console.error('Failed to process file:', file.name, err);
+        }
+    }
+
+    uploadBtn.textContent = '✓ ' + saved + ' photo' + (saved !== 1 ? 's' : '') + ' added';
+    loadRecentPhotos();
+    setTimeout(() => {
+        uploadBtn.disabled = false;
+        uploadBtn.textContent = '🖼️ Upload from Library';
+    }, 1500);
+
+    e.target.value = '';
+});
+
 // ---- Live camera viewfinder ----
 async function openCamera() {
     sessionCount = 0;