[Feature] Cleaning ceremony to remove stale temp/scratch files #791

Cleaning Ceremony

Problem

Even with a dedicated temp directory, files accumulate over time:

• Old session logs
• Stale orchestration logs
• Abandoned worktree artifacts
• Expired decision inbox files that were never merged
• Old observation archive files

Proposed solution

Add a built-in cleanup ceremony that runs:

• Automatically: After every 10 Ralph rounds (configurable)
• Manually: User says "clean up" or "housekeeping"

What it cleans

1. .squad/.tmp/ — delete everything (it's temp)
2. .squad/orchestration-log/ — archive entries older than 30 days
3. .squad/log/ — archive entries older than 30 days
4. Repo root — scan for known temp file patterns and move to .squad/.tmp/
5. Stale worktrees — remove worktrees for merged branches
6. Stale decision inbox files — warn about inbox files older than 7 days

Implementation

• New capability in watch: cleanup plugin
• New ceremony in ceremonies.md: cleanup with when: 'after' trigger
• Scribe handles the actual file operations (already owns .squad/ state)