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/search.ts

@@ -0,0 +1,65 @@
+/**
+ * public/search.ts — scrollback search box for the active terminal (M1).
+ *
+ * Adds a 🔍 button to the toolbar that toggles a small search overlay.
+ * Enter = next, Shift+Enter = previous, Esc = close.
+ */
+
+export interface SearchHooks {
+  find: (query: string, dir: 'next' | 'prev') => void
+  clear: () => void
+}
+
+function makeBtn(label: string, title: string): HTMLButtonElement {
+  const b = document.createElement('button')
+  b.textContent = label
+  b.title = title
+  b.setAttribute('aria-label', title)
+  return b
+}
+
+export function mountSearch(toolbar: HTMLElement, hooks: SearchHooks): void {
+  const box = document.createElement('div')
+  box.id = 'searchbox'
+  box.style.display = 'none'
+
+  const input = document.createElement('input')
+  input.type = 'text'
+  input.className = 'search-input'
+  input.placeholder = 'Search scrollback…'
+
+  const prev = makeBtn('↑', 'Previous match (Shift+Enter)')
+  const next = makeBtn('↓', 'Next match (Enter)')
+  const close = makeBtn('×', 'Close (Esc)')
+  box.append(input, prev, next, close)
+  document.body.appendChild(box)
+
+  const open = (): void => {
+    box.style.display = 'flex'
+    input.focus()
+    input.select()
+  }
+  const hide = (): void => {
+    box.style.display = 'none'
+    hooks.clear()
+  }
+
+  input.addEventListener('keydown', (e) => {
+    if (e.key === 'Enter') {
+      e.preventDefault()
+      hooks.find(input.value, e.shiftKey ? 'prev' : 'next')
+    } else if (e.key === 'Escape') {
+      e.preventDefault()
+      hide()
+    }
+    e.stopPropagation()
+  })
+  prev.addEventListener('click', () => hooks.find(input.value, 'prev'))
+  next.addEventListener('click', () => hooks.find(input.value, 'next'))
+  close.addEventListener('click', hide)
+
+  const toggle = makeBtn('🔍', 'Search scrollback')
+  toggle.className = 'toolbtn'
+  toggle.addEventListener('click', () => (box.style.display === 'none' ? open() : hide()))
+  toolbar.appendChild(toggle)
+}