Closeout suggests invalid planning summary command

[rickardvh]

Dogfooding #1212 closeout produced a next-safe-action entry with this command:

agentic-workspace planning summary --target . --format json

That command is invalid; the planning subcommand has no summary action. The working command is the top-level summary surface:

uv run agentic-workspace summary --target . --format json

Expected behavior:

• Closeout result actions should only suggest valid current CLI commands.
• If the message intends the top-level summary router, emit agentic-workspace summary ..., not agentic-workspace planning summary ....
• Add a focused regression test for closeout action command text.

Dogfooding evidence from this branch:

• uv run agentic-workspace planning closeout windows-static-proof-stability ... --format json returned the invalid next safe action.
• Running the suggested command failed with argparse invalid-choice output.
• Running uv run agentic-workspace summary --target . --format json succeeded.