Initial commit — Tauri image gallery with sqlite-vec

Sets up Tauri v2 + React frontend with SQLite metadata store,
sqlite-vec for CLIP embedding infrastructure, and r2d2 connection
pool replacing the single Arc<Mutex<Connection>>. Indexer now uses
rayon for parallel file metadata collection.

src/index.css

@@ -0,0 +1,32 @@
+@import "tailwindcss";
+
+* {
+  box-sizing: border-box;
+}
+
+html,
+body,
+#root {
+  height: 100%;
+  margin: 0;
+  padding: 0;
+  background: #030712;
+  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
+  -webkit-font-smoothing: antialiased;
+}
+
+/* Custom scrollbar */
+::-webkit-scrollbar {
+  width: 6px;
+  height: 6px;
+}
+::-webkit-scrollbar-track {
+  background: transparent;
+}
+::-webkit-scrollbar-thumb {
+  background: rgba(255, 255, 255, 0.1);
+  border-radius: 3px;
+}
+::-webkit-scrollbar-thumb:hover {
+  background: rgba(255, 255, 255, 0.2);
+}