v0.7.3 — gate --summary/--json, in-place integrate refresh

Veridge 0.7.3

Integration & CI ergonomics. No engine changes — the graph, queries and zero-dependency core are
identical to 0.7.2.

New

• veridge gate --summary — counts + verdict only, without the per-reference detail list.
  Handy for large repos and CI logs.
• veridge gate --json — machine-readable result (ok, broken, stale, orphans, plus the
  full broken_refs list) for wiring gate into CI. Exit code is unchanged: 0 clean, 1 drift.

Fixed

• veridge integrate refreshes the steering note in place. Re-running it on an already-wired
  project replaces the <!-- veridge:start -->…<!-- veridge:end --> block in CLAUDE.md/
  AGENTS.md with the current directive, instead of skipping because the marker was already
  present. Surrounding content is preserved and the operation stays idempotent. Previously,
  projects wired with an older version kept a stale note — now veridge integrate claude|codex
  brings them up to date.

The gate --summary mode comes from a real evaluation of Veridge on a large TypeScript monorepo.