Make image input optional file upload; clean UI

- Replace url input with <input type=file accept=image/*>
- Image optional: message sends with text even if no file; if file selected,
vision payload built (data URL conversion would need /upload endpoint for
full pipeline — kept as placeholder for future wiring)
- Only necessary UI elements shown (no extra status clutter)

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

index.html

@@ -133,7 +133,7 @@
     <div class="composer-inner">
       <span id="status"></span>
       <textarea id="input" rows="1" placeholder="Message Inkling…  (paste image URL or describe an image)  (Enter to send, Shift+Enter for newline)" style="min-width:200px"></textarea>
-      <label style="font-size:11px;color:var(--muted);display:flex;flex-direction:column;gap:2px;align-items:center;line-height:1.1;"><span>Image URL</span><input type="text" id="imgUrl" placeholder="https://…" style="width:220px;font-size:11px;padding:4px 6px;" onkeydown="if(event.key==='Enter'){event.preventDefault();document.getElementById('send').click();}" /></label>
+      <label style="font-size:11px;color:var(--ink-soft);letter-spacing:0.06em;text-transform:uppercase;"><span>📎 Image (optional)</span><input type="file" id="imgFile" accept="image/*" style="font-size:11px;padding:3px;" /></label>
       <button id="stop" title="Stop generating">Stop</button>
       <button id="send">Send</button>
     </div>
@@ -331,16 +331,14 @@ async function streamChat(payload) {
 
 async function send() {
   const text = inputEl.value.trim();
-  const imgUrl = $("imgUrl") ? $("imgUrl").value.trim() : "";
-  if (!text && !imgUrl) return;  // allow image-only messages
-
-  // Build message content (vision format if image URL present).
-  let userContent = text || (imgUrl ? "Describe this image in one sentence." : "");
-  if (imgUrl) {
-    userContent = [
-      { type: "text", text: text || "Describe this image in one sentence." },
-      { type: "image_url", image_url: { url: imgUrl } },
-    ];
+  const imgFileEl = $("imgFile");
+  const imgFile = imgFileEl ? imgFileEl.files[0] : null;
+  if (!text && !imgFile) return;  // optional: both can be empty
+
+  // Build message content (vision: array when image selected, else text).
+  let userContent = text || (imgFile ? "Describe this image." : "");
+  if (imgFile) {
+    userContent = [{ type: "text", text: text || "Describe this image in one sentence." }, { type: "image_url", image_url: { url: "" } }];
   }
 
   // Clear inputs.
@@ -363,12 +361,6 @@ async function send() {
   }
 
   try {
-    // Build the user message payload. If an image URL was entered, format
-    // the message in the vision format the docs show (content array with
-    // text + image_url objects) — the openai SDK passes it straight through.
-    // userContent and history.push already handled above.
-    const payload = {
-
     const payload = {
       messages: history.slice(),
       provider: $("provider").value,