powerqueue v0.11.0

The queue's policy can live in the repository: .powerqueue.toml now carries
[linear], [github], [scheduler] and the rules file, and the daemon can
read it from the default branch instead of the working tree.

Added

• .powerqueue.toml accepts [linear] (everything but endpoint),
  [github] (everything but endpoint), [scheduler] (everything but
  gh_binary) and priority_file (the rules file, relative to the repo
  root). Precedence is repo over global, key by key; lists replace. Secrets,
  [budget] and host settings stay global.
• repo.overrides_from = "default-branch" reads .powerqueue.toml and a
  relative priority_file as committed on origin/<default_branch> (the
  local branch without a remote), so a git checkout in the main checkout
  cannot change what the daemon runs; repo.fetch_interval_secs (300) makes
  the daemon fetch while idle so a merged change arrives on its own. The
  default stays "working-tree".
• The daemon reloads its configuration when .powerqueue.toml changes
  (working tree: mtime and size; branch: blob ids), without config set or a
  restart: events daemon.reloaded (with the keys taken and the commit) and
  daemon.reload_failed (the previous configuration is kept). Committed
  rules reload the same way; rules.loaded names the commit.
• config show marks every key that came from the repository
  (# .powerqueue.toml) and names the file and branch; --json adds
  repo_overrides. config validate validates the merged configuration and
  reports what the repo sets. config path lists repo_config.
• doctor: the .powerqueue.toml check reports the source and the keys set
  and fails when the branch cannot be read; a new overrides source check
  warns when the main checkout is not on the default branch (working-tree
  mode), when default-branch mode has no remote branch to read, or when the
  daemon never fetches. The PRIORITY.md check reads the committed copy when
  that is what the daemon reads.
• priority show|check|explain|simulate read the committed rules when the
  daemon does and say so; priority edit reminds you to commit and push;
  tune refuses to rewrite a rules file the repository owns.

Changed

• Shorten the README to an overview and quick start with a Mermaid workflow;
  move detailed guides and references into docs/. The tuning assistant now
  embeds the dedicated configuration reference.