[amplifier-app-cli] Rich markup error when session resume error contains path-like strings

Problem

When amplifier session resume fails, the error message is printed using Rich markup without escaping user data:

console.print(f"[red]Error resuming session:[/red] {exc}")

If the error message contains path-like strings (e.g., /Users/foo/bar), Rich interprets [/Users] as a closing markup tag and crashes:

rich.errors.MarkupError: closing tag '[/Users]' at position 48 doesn't match any open tag

This masks the actual error, making debugging difficult.

Locations

• amplifier_app_cli/commands/session.py line 514
• amplifier_app_cli/commands/session.py line 1086

Both have the same pattern.

Suggested Fix

from rich.markup import escape
# ...
console.print(f"[red]Error resuming session:[/red] {escape(str(exc))}")

Reproduction

1. Trigger any session resume error that includes a macOS path in the exception message
2. Observe Rich crashes instead of showing the actual error

Start in amplifier_app_cli/commands/session.py at lines 514 and 1086, where session resume errors are printed, and reproduce the failure with an exception containing a macOS-style path. Done means both locations display the original error without a Rich MarkupError; the issue does not name a test file to run.