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/terminal-session.ts

@@ -10,6 +10,8 @@
 
 import { Terminal } from '@xterm/xterm'
 import { FitAddon } from '@xterm/addon-fit'
+import { SearchAddon } from '@xterm/addon-search'
+import { WebLinksAddon } from '@xterm/addon-web-links'
 import type { ClientMessage, ServerMessage } from '../src/types.js'
 import { folderFromTitle } from './title-util.js'
 
@@ -56,6 +58,7 @@ export class TerminalSession {
 
   private readonly term: Terminal
   private readonly fitAddon: FitAddon
+  private readonly searchAddon: SearchAddon
   private readonly resizeObserver: ResizeObserver
   private readonly onSessionId: (id: string) => void
   private readonly onActivity: (() => void) | undefined
@@ -92,6 +95,9 @@ export class TerminalSession {
     })
     this.fitAddon = new FitAddon()
     this.term.loadAddon(this.fitAddon)
+    this.searchAddon = new SearchAddon()
+    this.term.loadAddon(this.searchAddon)
+    this.term.loadAddon(new WebLinksAddon()) // M2: tap a URL Claude prints to open it
     this.term.open(this.el)
 
     this.term.onData((data) => this.send(data))
@@ -244,6 +250,17 @@ export class TerminalSession {
     this.ws.send(buildMessage({ type: 'input', data }))
   }
 
+  /** Scrollback search (M1). */
+  findNext(query: string): void {
+    this.searchAddon.findNext(query)
+  }
+  findPrevious(query: string): void {
+    this.searchAddon.findPrevious(query)
+  }
+  clearSearch(): void {
+    this.searchAddon.clearDecorations()
+  }
+
   /** Make this pane visible, fit it, and focus it. */
   show(): void {
     this.el.style.display = 'block'