0.11.0 — a measurement an agent can type is not a measurement

One release, one lesson: a measurement an agent can type is not a
measurement. Everything here came from two live runs at the capability
floor the day 0.10.0 shipped.

Added

• jig probe --save <surface>. The CLI writes the probe file now. It
  reads what the probe returned on stdin, checks it is probe output for a
  page inside the project, and stamps it with that page's checksum and the
  time. A run had written its own probe file by hand — five links and an
  Escape key that closed a menu with thirteen links and no Escape handler —
  and its review passed on those numbers.
• install --hook / --no-hook. The Stop hook is opt-in. An
  interactive install offers it once and takes silence as no; --yes never
  adds it, because that is the path an agent takes and nobody is there to
  consent. update moves an existing hook and never adds one.

Changed

• Probe files are version 2. jig verdicts rejects a probe with no
  stamp — nothing measured it — and one whose page changed after it was
  taken. Version 1 files no longer validate.
• README and init say which directory to commit, and why. The tokens
  live in <css dir>/jig/; .jig/ holds state.json, specs, mockups and
  critique verdicts. Both are warned about separately, each with what
  ignoring it costs. Since 0.7.0 both had said .jig/ holds the tokens.