fix(cli): preload deferred rich/typer modules before in-place upgrade

[groksrc]

Problem

Every successful bm update (Homebrew or uv tool install) ends with a crash from the old process:

ImportError: cannot import name 'rich_utils' from 'typer' ...
ModuleNotFoundError: No module named 'rich._emoji_codes'

brew upgrade basic-memory removes the old keg (e.g. Cellar/basic-memory/0.21.6/) while the 0.21.6 Python process that launched it is still running. When run_auto_update returns and the CLI prints the final status via rich, rich lazily imports rich._emoji_codes from files that no longer exist — and typer's excepthook then fails the same way trying to lazily import typer.rich_utils to render the traceback. The upgrade itself succeeds; it's the dying process crashing on its last words.

Fix

Import both deferred modules in run_auto_update immediately before launching the upgrade subprocess, while this install's files still exist. Covers both bm update and the periodic auto-update path.

Verification

• New regression test pops the modules from sys.modules, calls the preload, asserts they're back.
• uv run pytest tests/cli/test_auto_update.py tests/cli/test_update_command.py — 24 passed.
• just lint + just typecheck clean.

🤖 Generated with Claude Code

[groksrc]

CI note: the Test SQLite Integration (ubuntu-latest, Python 3.14) failure was test_mcp_sse_forces_local, the known timing flake tracked in #940 (this PR doesn't touch the MCP command path). Re-ran the failed job.