Add video proxy to fix Firefox tracking protection blocking Twitter videos

Twitter's video.twimg.com CDN is blocked by Firefox's Enhanced Tracking
Protection when loaded cross-origin. This adds a server-side proxy that
streams videos through our domain.

- Add /proxy/video/{id} endpoint to proxy embed video URLs
- Update embed video player: click-to-play with overlay, muted, looping
- Show native controls on hover

internal/static/css/app.css

@@ -296,6 +296,40 @@ button, input, textarea, select {
 	width: 100%;
 }
 
+.video-container {
+	position: relative;
+}
+
+.video-overlay {
+	position: absolute;
+	inset: 0;
+	display: flex;
+	align-items: center;
+	justify-content: center;
+	background: rgba(0, 0, 0, 0.3);
+	cursor: pointer;
+	transition: background 0.15s ease;
+}
+
+.video-overlay:hover {
+	background: rgba(0, 0, 0, 0.4);
+}
+
+.video-overlay .play-button {
+	width: 4rem;
+	height: 4rem;
+	background: rgba(0, 0, 0, 0.7);
+	color: #fff;
+	border-radius: 50%;
+	display: flex;
+	align-items: center;
+	justify-content: center;
+	font-size: 1.5rem;
+	padding-left: 0.25rem;
+}
+
+
+
 .embed-container {
 	position: relative;
 }

internal/static/js/app.js

@@ -378,6 +378,19 @@ async function deleteItem(id) {
 	}
 }
 
+// Play video (initial click to start)
+function playVideo(overlay) {
+	const container = overlay.parentElement;
+	const video = container.querySelector('video');
+	if (video) {
+		video.play();
+		overlay.remove();
+		// Show controls on hover
+		video.addEventListener('mouseenter', () => video.controls = true);
+		video.addEventListener('mouseleave', () => video.controls = false);
+	}
+}
+
 // Utility
 function escapeHtml(str) {
 	const div = document.createElement('div');