v0.0.1

First public release. perturb was developed privately under the name planner; nothing was
published under that name. Repositories that used a private build need these changes:

Changed

• Renamed. The command is perturb, the committed ledger is perturb/ (was planning/), and
  the local cache is .perturb/ (was .planner/).
• The label marking a planned issue is ready-to-implement (was hardened), configurable as
  labels.ready_to_implement in perturb/config.yaml.
• perturb show plan:<slug> reports files, the plan's declared files, instead of cycles.

Added

• perturb/config.yaml sets where plans, friction logs and audits live, and which labels mark
  epics and ready issues.
• PERTURB_GH names the GitHub CLI to call; the default is gh.
• Friction logs can list their commits in front-matter (commits:).
• perturb init adds .perturb/ to .gitignore, creating the file if needed.
• An ADR can supersede a single consequence of an earlier one:
  supersedes: ["adr:0003#postgres-over-sqlite"] raises supersede events only to the issues that
  acknowledged that consequence, and perturb check reports entries that don't resolve.
• Every verb has --help with a description of the verb and each argument.

Fixed

• perturb adr migrate no longer drops text silently. A **Supersedes:** line naming whole
  ADRs is carried into supersedes; one it can't interpret stays in the body with a warning, as
  does any annotation on the status line. Prose between the status line and the first heading is
  kept.