feat: doctor and adopt #4

Goal

A repository whose identity or location is wrong is reported, and the mechanical cases can be
fixed in place.

Context

• Trigger: fourth milestone, independent of the fleet issue and runnable in parallel with it.
• Affected: internal/doctor, cmd/gitcd.

This milestone is the fleet wide form of gitcd profile show, which the identity issue already
builds for a single repository. doctor is a loop over scan plus the global include checks.

The riskiest failure the tool exists to prevent is a commit landing under the wrong identity and
nobody noticing until it reaches a work remote. These checks are the last of the four defences
against it, after user.useConfigOnly, the clone read back and profile show.

Acceptance criteria

• gitcd doctor reports a repository whose effective identity differs from the profile its
  rules imply, and names both.
• It reports a repository under root sitting at a path the layout would not render.
• It reports a missing or stale include block in ~/.config/gitcd/includes.gitconfig.
• It reports a global identity key positioned after the gitcd include, which would win
  silently.
• It reports a case mismatch between a rendered glob and the on disk spelling.
• It distinguishes a deliberate pin, marked by gitcd.profile, from stale config.
• It prints both config homes, ~/.gitcd.yaml and ~/.config/gitcd/, so neither surprises
  the user.
• gitcd doctor --fix repairs the stale include block, the ordering and the case mismatches,
  and never touches identity keys it did not write.
• gitcd adopt <path> moves an existing clone into the layout, fixes its config, prints the
  old and the new path, and asks before moving.
• gitcd adopt refuses a repository with extensions.worktreeConfig enabled rather than
  guessing which config file to write.
• Exit code is non zero when any finding is reported, so CI and a shell prompt can use it.
• Tests cover one fixture per finding.
• task check passes.

Out of scope

• migrate for a changed layout template. adopt in a loop covers it until the layout changes.
• status and sync.