fix(sidebar): icon-only submit button — no more text overlap

Replace 'Index Repo' text with arrow SVG icon (→), same pattern as
Linear/Raycast search inputs. Button is now a fixed 36px square so
the input placeholder has room to breathe. Spinner icon shown while indexing.

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

ui/src/components/Sidebar.jsx

@@ -306,8 +306,11 @@ export default function Sidebar({ repos, reposLoading, activeRepo, onSelectRepo,
             onChange={(e) => setUrl(e.target.value)}
             disabled={isIngesting}
           />
-          <button className="btn" type="submit" disabled={isIngesting || !url.trim()}>
-            {isIngesting ? "Indexing…" : "Index Repo"}
+          <button className="btn" type="submit" disabled={isIngesting || !url.trim()} title="Index repository">
+            {isIngesting
+              ? <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2.5" strokeLinecap="round"><path d="M12 2v4M12 18v4M4.93 4.93l2.83 2.83M16.24 16.24l2.83 2.83M2 12h4M18 12h4M4.93 19.07l2.83-2.83M16.24 7.76l2.83-2.83"/></svg>
+              : <svg width="14" height="14" viewBox="0 0 16 16" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round"><path d="M3 8h10M9 4l4 4-4 4"/></svg>
+            }
           </button>
         </form>
         {/* Curated repos — quick-start for new users */}

ui/src/index.css

@@ -360,8 +360,8 @@ textarea:focus-visible {
   color: var(--text);
   font-size: 12px;
   font-family: var(--mono);
-  /* Right padding must clear the "Index Repo" button (~90px wide + 10px gap) */
-  padding: 11px 108px 11px 13px;
+  /* Right padding clears the icon button (36px) + gap */
+  padding: 11px 48px 11px 13px;
   outline: none;
   transition: border-color 180ms ease, box-shadow 180ms ease;
   width: 100%;
@@ -378,17 +378,18 @@ textarea:focus-visible {
   font-family: var(--mono);
 }
 
-/* Submit button — glass pill inside the input, white text always ───────── */
+/* Submit button — icon-only square button inside the input ─────────────── */
 .ingest-form .btn {
   position: absolute !important;
   right: 5px;
   top: 5px;
   bottom: 5px;
   height: auto;
-  padding: 0 12px;
-  font-size: 11px;
-  font-weight: 600;
-  letter-spacing: 0.02em;
+  width: 36px;
+  padding: 0;
+  display: flex;
+  align-items: center;
+  justify-content: center;
   border-radius: 7px;
   color: #ffffff !important;
   /* Solid enough to read white text clearly, with top-edge shimmer */