Loki Mode v7.19.3

Added

• Shareable proof-of-run: the proof HTML (loki proof) now renders a branded
  in-page card (what was built, verified, cost, duration, with Loki/Autonomi
  branding) and opt-in share buttons (X/Twitter, LinkedIn, Copy link). The
  local proof file stays ZERO-EGRESS by default (the v7.18.2 posture): no
  og:image, no external assets, no literal social URLs in the static HTML, and
  no network call on load. Share intent URLs are assembled in JavaScript at
  click time, so a button is inert until the user clicks it. The card and the
  social hook render only from the already-redacted proof data, and an
  operator-provided publish URL (LOKI_PROOF_PUBLIC_URL) is threaded through
  the same redaction before it can appear anywhere. Opt out of the buttons with
  LOKI_PROOF_SHARE_BUTTONS=0.

NOT tested in this release (honest disclosure)

• A rich social-media preview (og:image) requires publishing to an
  HTML-serving host that returns a public URL (the LOKI_HOSTED_ENDPOINT
  seam). loki proof share to a GitHub Gist does NOT yield a rich preview: the
  gist page serves GitHub's own preview tags and the raw file is served as
  text/plain, which social scrapers do not parse. There is no official Loki
  hosted backend yet; the seam is honest about this.
• LinkedIn's share URL ignores prefilled text (it only scrapes the
  destination's preview tags), so a LinkedIn preview depends entirely on the
  hosted og:image being present. The X intent URL carries the prefilled hook.
• Sharing is fully manual and opt-in; there is no automatic posting and no
  hosted discovery gallery in this release.
• Verification is the proof generator against per-case fixtures (41 assertions,
  including the zero-egress self-containment guard and the
  LOKI_PROOF_SHARE_BUTTONS opt-out being genuinely consumed), not a live
  end-to-end published share.