feat: shell terminal, virtual keyboard fixes, settings font slider

- Add shell terminal: new tmux window spawned at project cwd, opened
  from the Terminal icon in the ChatView header; ShellTerminalView lets
  you navigate back to chat or jump to the Claude tmux terminal mode
- Fix system keyboard appearing on first terminal launch: ghostty-web
  calls focus() on a contenteditable div inside open(), triggering iOS
  keyboard before we can suppress it; patch HTMLElement.prototype.focus
  as a no-op for the synchronous duration of terminal.open()
- Add keyboard font-size slider in Settings
- Fix virtual keyboard button corner radius and depth scaling with key height
- Fix keybar gap/padding proportionality via heightScale factor
- Cap keybar font size so it does not grow when bar height is increased

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

src/components/TerminalView.tsx

@@ -0,0 +1,75 @@
+import { useEffect, useRef, useImperativeHandle, forwardRef } from 'react';
+import { STORAGE } from '../lib/storage-keys';
+import { WebTerminal } from '../lib/terminal/WebTerminal';
+import type { TerminalConfig } from '../lib/terminal/terminal-config';
+
+interface TerminalViewProps {
+  sessionId: string;
+  adapter?: string;
+  style?: React.CSSProperties;
+}
+
+export interface TerminalViewHandle {
+  closeKeyboard(): void;
+}
+
+function buildTerminalWsUrl(sessionId: string, adapter?: string): string {
+  const proto = location.protocol === 'https:' ? 'wss' : 'ws';
+  const token = localStorage.getItem(STORAGE.TOKEN) ?? '';
+  const adapterParam = adapter ? `&adapter=${encodeURIComponent(adapter)}` : '';
+  return `${proto}://${location.host}/terminal/${encodeURIComponent(sessionId)}?token=${encodeURIComponent(token)}${adapterParam}`;
+}
+
+const TERMINAL_CONFIG: TerminalConfig = {
+  fontSize: 14,
+};
+
+export const TerminalView = forwardRef<TerminalViewHandle, TerminalViewProps>(
+  function TerminalView({ sessionId, adapter, style }, ref) {
+    const containerRef = useRef<HTMLDivElement>(null);
+    const termRef = useRef<WebTerminal | null>(null);
+
+    useImperativeHandle(ref, () => ({
+      closeKeyboard() {
+        termRef.current?.closeKeyboard();
+      },
+    }));
+
+    useEffect(() => {
+      const el = containerRef.current;
+      if (!el) return;
+
+      const wsUrl = buildTerminalWsUrl(sessionId, adapter);
+      let cancelled = false;
+
+      WebTerminal.create(el, wsUrl, TERMINAL_CONFIG).then((t) => {
+        if (cancelled) {
+          t.dispose();
+          return;
+        }
+        termRef.current = t;
+      }).catch((err) => {
+        console.error('[TerminalView] Failed to create terminal:', err);
+      });
+
+      return () => {
+        cancelled = true;
+        termRef.current?.dispose();
+        termRef.current = null;
+      };
+    }, [sessionId, adapter]);
+
+    return (
+      <div
+        ref={containerRef}
+        style={{
+          width: '100%',
+          height: '100%',
+          backgroundColor: '#000',
+          overflow: 'hidden',
+          ...style,
+        }}
+      />
+    );
+  }
+);