Adopt the global ~/Projects/.worktrees convention

[Vinosaamaa]

Goal

Adopt the cross-project worktree convention defined by terminal-environment-toolkit #123: future owned-task worktrees default to ~/Projects/.worktrees/<repository>-<issue>-<slug>.

Repository work

• Make repository instructions defer to the source-managed universal worktree-root rule rather than inventing another location.
• Update any repository-owned launcher, queue, resume, cleanup, or automation path to consume a configured worktree root whose default is ~/Projects/.worktrees.
• Inventory existing registered worktrees with git worktree list --porcelain and bind them to their issue/task, branch, publication state, dirty state, and active runtime before migration.
• Move only inactive, clean, unambiguous worktrees through supported Git worktree operations.
• Preserve active, dirty, unpublished, ambiguous, temporary-test, or externally managed worktrees until their owning lifecycle permits a safe move or cleanup.
• Never delete, recreate, or stash existing work merely to satisfy the new layout.

Acceptance criteria

• New issue-owned worktrees use the global default unless an explicit repository configuration documents an exception.
• Existing worktrees have a complete migration ledger with moved, preserved, or cleanup_pending status and exact reasons.
• Resume, cleanup, and task/runtime records remain correct after any path migration.
• Focused tests reject silently hard-coded alternative roots.
• No active or unpublished work is lost, duplicated, or detached from its owning issue.

This is future migration work. It does not authorize moving or deleting any current worktree from the issue-authoring action.