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>

server/terminal-session.ts

@@ -0,0 +1,106 @@
+import * as nodePty from 'node-pty';
+import type { IPty } from 'node-pty';
+import { EventEmitter } from 'events';
+
+interface PtyEntry {
+  pty: IPty;
+  sessionId: string;
+  windowId: string;
+  dataListeners: Set<(data: string) => void>;
+  exitListeners: Set<() => void>;
+  onDataHandler: (data: string) => void;
+}
+
+/**
+ * Manages PTY processes for terminal sessions. Each call to getOrCreate
+ * spawns `tmux attach-session -t clawtap:<windowId>` as a node-pty process,
+ * giving a full bidirectional terminal stream into the existing tmux pane.
+ *
+ * One PTY per (sessionId, clientId) tuple — multiple clients attach
+ * independently via separate tmux attach processes.
+ */
+export class PtySessionManager extends EventEmitter {
+  private ptys = new Map<string, PtyEntry>(); // key = `${sessionId}:${clientId}`
+
+  getOrCreate(sessionId: string, windowId: string, clientId: string, cols = 80, rows = 24): PtyEntry {
+    const key = `${sessionId}:${clientId}`;
+    const existing = this.ptys.get(key);
+    if (existing) return existing;
+
+    const pty = nodePty.spawn('tmux', ['attach-session', '-t', `clawtap:${windowId}`], {
+      name: 'xterm-256color',
+      cols,
+      rows,
+      env: process.env as Record<string, string>,
+    });
+
+    const entry: PtyEntry = {
+      pty,
+      sessionId,
+      windowId,
+      dataListeners: new Set(),
+      exitListeners: new Set(),
+      onDataHandler: () => {},
+    };
+
+    entry.onDataHandler = (data: string) => {
+      for (const cb of entry.dataListeners) cb(data);
+    };
+
+    pty.onData(entry.onDataHandler);
+    pty.onExit(() => {
+      this.ptys.delete(key);
+      for (const cb of entry.exitListeners) cb();
+    });
+
+    this.ptys.set(key, entry);
+    return entry;
+  }
+
+  onData(sessionId: string, clientId: string, cb: (data: string) => void): () => void {
+    const key = `${sessionId}:${clientId}`;
+    const entry = this.ptys.get(key);
+    if (!entry) return () => {};
+    entry.dataListeners.add(cb);
+    return () => entry.dataListeners.delete(cb);
+  }
+
+  onExit(sessionId: string, clientId: string, cb: () => void): () => void {
+    const key = `${sessionId}:${clientId}`;
+    const entry = this.ptys.get(key);
+    if (!entry) return () => {};
+    entry.exitListeners.add(cb);
+    return () => entry.exitListeners.delete(cb);
+  }
+
+  write(sessionId: string, clientId: string, data: string): void {
+    const key = `${sessionId}:${clientId}`;
+    this.ptys.get(key)?.pty.write(data);
+  }
+
+  resize(sessionId: string, clientId: string, cols: number, rows: number): void {
+    const key = `${sessionId}:${clientId}`;
+    this.ptys.get(key)?.pty.resize(cols, rows);
+  }
+
+  destroy(sessionId: string, clientId: string): void {
+    const key = `${sessionId}:${clientId}`;
+    const entry = this.ptys.get(key);
+    if (!entry) return;
+    entry.dataListeners.clear();
+    entry.exitListeners.clear();
+    try { entry.pty.kill(); } catch {}
+    this.ptys.delete(key);
+  }
+
+  destroyAll(): void {
+    for (const [key, entry] of this.ptys) {
+      entry.dataListeners.clear();
+      entry.exitListeners.clear();
+      try { entry.pty.kill(); } catch {}
+      this.ptys.delete(key);
+    }
+  }
+}
+
+export const ptyManager = new PtySessionManager();