polish(v0.6): replace toolbar emoji with themed line icons + hover tooltips

The glossy emoji (🔍⚙▦🕘⌨🔗📱) clashed with the Amber dark theme. Swap them
for clean lucide line icons (MIT, stroke=currentColor) so they take the theme
colour — muted by default, Amber on hover — and add a styled CSS hover tooltip
(data-tip, right-anchored so it never clips the edge) showing what each does.

- public/icons.ts: 7 line icons (search/settings/dashboard/history/keyboard/
  share/device), script-generated from lucide
- 7 toolbar modules: innerHTML = ICON_* + data-tip + aria-label
- style.css .toolbtn: 18px svg, --text-dim → --accent on hover, [data-tip] tooltip

Frontend-only. web typecheck + build clean; bundle has 0 toolbar emoji; verified
in-browser: line icons in theme colour, amber + tooltip on hover.

public/search.ts

@@ -10,6 +10,8 @@ export interface SearchHooks {
   clear: () => void
 }
 
+import { ICON_SEARCH } from './icons.js'
+
 function makeBtn(label: string, title: string): HTMLButtonElement {
   const b = document.createElement('button')
   b.textContent = label
@@ -58,8 +60,11 @@ export function mountSearch(toolbar: HTMLElement, hooks: SearchHooks): void {
   next.addEventListener('click', () => hooks.find(input.value, 'next'))
   close.addEventListener('click', hide)
 
-  const toggle = makeBtn('🔍', 'Search scrollback')
+  const toggle = makeBtn('', '')
   toggle.className = 'toolbtn'
+  toggle.innerHTML = ICON_SEARCH
+  toggle.dataset.tip = 'Search'
+  toggle.setAttribute('aria-label', 'Search')
   toggle.addEventListener('click', () => (box.style.display === 'none' ? open() : hide()))
   toolbar.appendChild(toggle)
 }