fix(cli): wire classic sessions command

[LeonSGP43]

Summary

• add a classic CLI /sessions handler that reuses the shared session browser
• relaunch into the selected session instead of falling through to unknown command
• add regression tests for select, cancel, and empty-session flows

Testing

• ./.venv/bin/python -m pytest -q -o addopts= tests/cli/test_cli_init.py
• ./.venv/bin/ruff check .
• env -i PATH="/Library/Frameworks/Python.framework/Versions/3.10/bin:/usr/bin:/bin:/usr/sbin:/sbin" HOME="$HOME" TERM="${TERM:-xterm-256color}" TZ=UTC LANG=C.UTF-8 LC_ALL=C.UTF-8 PYTHONHASHSEED=0 ./.venv/bin/python -m pytest -o addopts= --collect-only --ignore=tests/integration --ignore=tests/e2e -m 'not integration'

[Bartok9]

Reviewed — correct fix. Closing my duplicate #23077. One note: the _show_recent_sessions(reason='sessions') call matches how other slash commands delegate to existing methods, which keeps the handler lean. Good pattern choice.

[teknium1]

Closing as already fixed on main.

Triage notes (high confidence):
origin/main cli.py:6618 already implements _handle_sessions_command and the elif at L8234 wires canonical == 'sessions' to it; the PR adds a parallel implementation that duplicates existing functionality.

If you still see this on the latest version, please reopen with reproduction steps.

(Bulk-closed during a CLI triage sweep.)