feat(v0.3): keybar Claude shortcuts + scrollback search + clickable links

- keybar: add Esc·Esc / ^O / ^T / ^B + per-button tooltips (KEY_MAP 14 keys)
- M1 search: @xterm/addon-search per terminal; 🔍 toolbar button + search box
  (Enter=next, Shift+Enter=prev, Esc=close)
- M2 links: @xterm/addon-web-links per terminal (tap URLs Claude prints)
- tab bar split into #tabs (scrollable) + #toolbar (utility cluster) for future
  utilities (QR/settings/dashboard)
- Browser-verified: 14 keybar buttons, search highlights matches, no console errors.
  199 tests green, typechecks + build ok.

public/style.css

@@ -36,12 +36,77 @@ html, body {
   border-bottom: 1px solid #3a3a3a;
   display: flex;
   align-items: stretch;
+  z-index: 1001;
+}
+
+/* tabs: scrollable; toolbar: fixed cluster on the right */
+#tabs {
+  flex: 1 1 auto;
+  display: flex;
+  align-items: stretch;
   overflow-x: auto;
   overflow-y: hidden;
-  z-index: 1001;
   scrollbar-width: thin;
 }
 
+#toolbar {
+  flex: 0 0 auto;
+  display: flex;
+  align-items: center;
+  border-left: 1px solid #3a3a3a;
+}
+
+.toolbtn {
+  background: none;
+  border: none;
+  color: #aaa;
+  cursor: pointer;
+  font-size: 15px;
+  padding: 0 12px;
+  height: 100%;
+}
+.toolbtn:hover {
+  color: #fff;
+  background-color: #2a2a2a;
+}
+
+/* Search box overlay (M1) */
+#searchbox {
+  position: fixed;
+  top: calc(var(--tabbar-h) + 6px);
+  right: 8px;
+  z-index: 1100;
+  display: flex;
+  gap: 4px;
+  padding: 6px;
+  background-color: #2a2a2a;
+  border: 1px solid #3a3a3a;
+  border-radius: 6px;
+  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
+}
+.search-input {
+  width: 180px;
+  padding: 4px 6px;
+  font: inherit;
+  font-size: 13px;
+  color: #fff;
+  background: #111;
+  border: 1px solid #444;
+  border-radius: 3px;
+  outline: none;
+}
+#searchbox button {
+  background: #333;
+  border: 1px solid #444;
+  color: #ddd;
+  cursor: pointer;
+  border-radius: 3px;
+  padding: 0 8px;
+}
+#searchbox button:hover {
+  background: #555;
+}
+
 .tab {
   display: flex;
   align-items: center;