Tooling: parallel worktrees with worktrunk, outside the repository and based on the release branch #265

Parallel bugfix and feature work runs in many worktrees at once (2.3.1 had ten PRs in flight). Today those are the desktop app's .claude/worktrees/<name>, kept out of git add -A only by .git/info/exclude, and agent worktrees start from origin/main, not the release branch.

Adopt worktrunk (wt) for it, adapted from a handoff measured in another repository:

• worktrees beside the repository (../CodoMetis.TypeKit-worktrees/<branch>), set per machine in worktrunk's user config;
• worktrunk's default branch set to the open release branch (wt config state default-branch set release/2.4.0), so wt switch -c, the Claude Code plugin's agent worktrees, wt remove and wt step prune all base on and judge "merged" against release/<version>, not main;
• .claude/worktrees/ in the tracked .gitignore;
• the Bash guard refuses wt merge and the wt step building blocks that squash, rebase or push into a target (squash, rebase, push): work reaches a release branch by a PR and a merge commit (decision 94);
• no .worktreeinclude and no copy hook: a fresh worktree needs no gitignored file to build (measured 2026-10-31: the solution cold in 27 s, the tools in 2 s, nothing copied in);
• a runbook linked from AGENTS.md, and a decision record.

Done when a worktree made by wt switch -c builds and tests from cold, the guard's new rule is shown to fail against a seeded defect, and the runbook says how to start, list, land and clean up.

The decision record is 0126: 0122 to 0124 are taken by the stack #188, #189, #190 and 0125 by the third-party-licenses work, so this lands after them (DesignRecordTests refuses a gap).