[preflight] PF-10 remove stale docs-philosophy worktree + document convention #70

What

Remove the stale .claude/worktrees/docs-philosophy worktree and document the worktree convention for TUI redesign phases.

Why

That worktree contains one unique commit (59ae215 chore: remove devloop self-control from CLAUDE.md) and a modified .claude/settings.json. Must verify the commit is merged or merge it before removing — currently DEFERRED pending user decision.

Acceptance criteria

• Decide: merge commit 59ae215 into main, OR confirm it can be dropped
• git worktree remove .claude/worktrees/docs-philosophy
• CLAUDE.md (project) documents worktree convention: .claude/worktrees/tui-phase-{0..4}

Notes

This issue is deferred until the user confirms what to do with the unique commit.