skillscript-runtime v0.20.2

Click-to-approve in the dashboard, without putting standing signing power on the
network surface.

• When SKILLSCRIPT_APPROVAL_PASSCODE is set (+ secured mode + a readable key),
  the dashboard mounts POST /unlock + POST /approve + GET /signing-status.
  The approver enters the passcode once per browser session to unlock
  signing; the dashboard then signs Approved skills with the operator's key.
• The unlock is in-memory, session-cookie-bound, and idle-expires (15 min) —
  the dashboard holds no standing signing power, only a live human-entered
  passcode unlocks it. /approve without a live unlock returns needs_passcode.
• The SPA shows a real Approve button (queue + skill detail) when signing is
  wired; clicking prompts for the passcode on the first approval of a session,
  then approves freely. Falls back to the copy-the-skillfile approve-command
  UX when signing isn't enabled.
• Default off (no passcode → routes 404, dashboard stays review-only).
  SECURITY: enabling this gives the dashboard process read access to the private
  key, so run it operator-side / isolated from the agent (the agent must have no
  network path to it and must not be able to read the passcode). .env now;
  vault/encrypted-key custody is the future hardening.