v0.5.1

Fixes that writing the documentation site turned up, and pitboard's facts about Claude Code
read again, from 2.1.284.

Added

• In pitboard-core, assumptions::read_on says which systems' builds a fact is read from,
  as the new assumptions::Platform.

Changed

• pitboard's facts about Claude Code are read from 2.1.284, and from its macOS build as well
  as its Linux one. The weekly check reported three facts moved from 2.1.281; all three were
  read from the Linux build, which has no keychain code, or from the runtime Claude Code
  ships in. The one real change is that Claude Code no longer moves its login to the
  plaintext file when the keychain is locked, and nothing in pitboard depends on the old
  behaviour.
• The README introduces pitboard and links to
  docs.usepitboard.com, where the guides and reference are.
• SECURITY.md is only the security policy: which versions get fixes, how to report a
  vulnerability, and what pitboard does and does not protect against. Where parked logins
  are kept and what leaves your machine are on
  Security and privacy.
• How to make a release, how to replace the update key, and the Sparkle and Homebrew
  measurements a release rests on, moved from CONTRIBUTING.md to RELEASING.md.
• How the code is laid out, and the measurements of macOS, Claude Code and Codex it rests
  on, moved to ARCHITECTURE.md.

Fixed

• pitboard status --fresh, and Refresh in the app, asked Anthropic or OpenAI again during
  a wait the service had asked for. The 0.3.0 notes and pitboard doctor said they did not.
  They keep that wait now, and still ask a service again after it could not be reached.
  When a service had never answered for an account and then could not be reached, pitboard
  said the account was rate limited.
• With PITBOARD_NO_ARGV=1, renewing a parked login too large for security's standard
  input spent its refresh token and then could not store the new one. The parked login was
  lost. pitboard refuses before asking the service now, and the parked login stays as it was.
• A switch whose login could not be read back said to run pitboard again, which only
  reads. It names the pitboard use that finishes or undoes the switch.
• With Codex's auth.json missing, pitboard doctor suggested pitboard use codex/<label>,
  which refuses while nothing is signed in. It says to sign in with codex login.
• The man page listed a page per command, such as pitboard-status(1), and none of them is
  installed. It sets out every command, with its arguments and options, on its one page.
• The app never said that Claude Code is not installed: it waited for a read to fail in a
  way no read does. It says so when it finds neither claude nor codex, and neither tool
  has a login or an enrolled account.

Security

• The menu bar app ignored PITBOARD_NO_ARGV, and so did daily renewal unless its
  scheduler set it. Either could pass a large login to security as an argument, which
  another process running as you could read while the call lasts. The app reads
  PITBOARD_NO_ARGV from its own environment, and a schedule installed while it is set
  keeps it.