v1.9.0

Added

• Shadow DOM piercing in form discovery + fill. `DiscoverForm`,
  `FillFormSemantic`, and every interaction tool that routes through
  `resolveSelector` (`type`, `click`, batch actions) now walk into
  open shadow roots. Inputs inside Lit / Stencil / Vue / React custom
  elements are discovered and fillable without changing call shape.
  Discovered inputs are tagged with a stable `data-scout-id` so
  subsequent fills round-trip across shadow boundaries.
• Attribute selectors in `QuerySelectorPiercing`. The flat-node
  matcher now handles `[attr="value"]` and `tag[attr="value"]` in
  addition to `#id`, `.class`, and bare tags. Lets piercing resolve
  the `data-scout-id` selectors emitted by form discovery without
  another evaluate round-trip.
• `resolveSelector` falls back to piercing before invoking the
  text / natural-language paths. Any selector that fails standard
  `document.querySelector` automatically retries against the flat
  DOM tree before the slower fallbacks run.

Tests

• New `agent/shadow_dom_test.go` covers the full discover → fill →
  click → submit loop against a custom element that wraps its form
  in an open shadow root.

Why this matters

Every Lit / Stencil / web-components admin UI (and every modern
design system that relies on shadow encapsulation) becomes
scout-drivable without per-app `data-test` escape hatches.