Rapp 0.4.0

Breaking changes

• Rapp now checks parsed command line values against declared option
  types instead of coercing them. Integer options require integer
  values, so values like 10.2 or true produce an error; float
  options still accept integer values (#18).
• Rapp now parses YAML with YAML 1.2 semantics. Bare yes and no
  non-Boolean option values are strings, not Boolean aliases. Boolean
  options still accept YAML 1.1 aliases such as yes, no, y, n,
  on, and off for backward compatibility.
• Command switches are now required by default. If a command is omitted,
  Rapp prints scoped help. Add #| required: false above the switch()
  to allow running without a command (#21).
• Boolean switch help now shows the command-line form that changes the
  default: foo <- FALSE shows --foo, foo <- TRUE shows --no-foo,
  and foo <- NA shows --foo / --no-foo. Passing values remains more
  permissive: switches accept explicit values such as --foo=false and
  --foo false. See the
  Boolean option behavior table for the full
  set of accepted forms (#28).

New features

• #| examples: annotations now add usage examples to --help output
  (#23).
• Boolean switches now do the expected thing for most users without
  additional configuration. For exceptional needs,
  #| negative_alias: false disables generated --no-* command-line
  aliases while keeping the positive alias and explicit value forms such
  as --foo=false (#24, #28).

Bug fixes

• Launcher front matter now accepts documented kebab-case option names,
  such as default-packages (#19).
• On Windows, tests now preserve the user PATH (#26).
• Rapp can now be installed from source on R versions before 4.0.0
  (#30).
• The installation docs now clarify that package apps are discovered as
  exec/*.R, installed without the .R extension by default, and
  installed to RAPP_BIN_DIR when set (#20).
• install_pkg_cli_apps() now adds the default ~/.local/bin install
  directory to the user's zsh profile on macOS when it is not already on
  PATH. It respects ZDOTDIR and warns if the profile cannot be
  updated (#35).
• On Windows, install_pkg_cli_apps() no longer replaces the current
  process PATH with only the user-level Path after adding launcher
  directories. It now avoids duplicate entries, uses a short path when
  available, and reports too-long user-level Path values with a
  remediation hint (#38).