feat(skills): delegate investigate and build, and build in a worktree

[gborges0727]

Why

investigate and build addressed "you" and named no agent. The session that loaded one read "you" as itself and ran every step inline. research never had this problem, because it names opus-medium and lists what the brief carries.

build also mentioned worktrees only in "Many tickets". A single build ran in the user's checkout.

What changed

skills/investigate/SKILL.md

• Three new sections at the top address the session that loads the skill.
  • "Who does it" says the session runs none of the phases. It sends a brief to opus-medium, or to sol-xhigh through codex-delegate when Codex is on.
  • "The brief" lists what the brief carries.
  • "When it returns" has the session rerun the reproducing command and run git status. The session then reports in chat and nowhere else.
• A new "The method" heading says everything below it addresses the subagent.
• The subagent cannot reach the user, so two phases changed.
  • Phase 3 ranks suspects from what the brief says changed recently.
  • "When no check can be built" sends back what the subagent tried and what it needs. The session asks the user, then sends the answer to the same subagent.

skills/build/SKILL.md

• "Who runs the loop" splits the work by where the ask lives.
  • A spec file or an issue sends the test loop to one subagent.
  • A build discussed in the conversation stays in the session, because a brief would have to retell the discussion.
• "Where the work happens" puts every build in a git worktree at ../<repo>-build-<slug> on branch build/<slug>.
  • Its first step removes leftover build worktrees whose work is committed on their branch.
  • It leaves a leftover that holds uncommitted work, and names it in the reply.
• "Finish" commits on the branch, then removes the worktree.
  • Git refuses to remove a worktree that holds untracked files, and the skill copies files such as a .env into it.
  • The skill adds --force only after git status --porcelain shows nothing but the files it copied in.
• A build that stops early keeps its worktree and reports the path with the command that discards it.
• "Build and commit" now means merging build/<slug> into the branch the user was on. The skill still never pushes.
• "Many tickets" makes the spec's worktree the same way and ends on "Finish".

Other files

• The build and investigate rows in README.md describe the new behaviour.
• The plugin version goes from 1.32.0 to 1.33.0 in both manifests.
• The rev goes from 38 to 39 in README.md and scripts/cloud-bootstrap.sh.

Testing

No session has run either skill with the new wording yet. I tested the git behaviour that "Finish" depends on in a scratch repo. git worktree remove removed a worktree holding an ignored .env. It refused one holding an untracked file, and --force removed it.