Add terminal-safe detached manager for short100 RG analysis

[charlesmartin14]

Adds a standalone lifecycle manager for the complete four-stage short100 RG analysis.

• launches the worker with start_new_session=True and detached stdio
• returns the prompt immediately; no tail -f and no caller shell options
• provides one-shot status and log commands
• provides a guarded stop for both managed and legacy nohup runs
• keeps all state, logs, data, figures, and HTML under /private/tmp
• documents the workflow and adds dependency-light contract tests

Local validation:

• bash -n passed
• managed start/status/stop lifecycle smoke passed
• three dependency-light contract tests passed when invoked directly
• full pytest was unavailable in the sandbox