Add intent browser ghost UI and schema-driven search rendering

[sarbadaj]

Summary

This PR adds the first concrete UI slice for Papillon’s intent-browser model.

Papillon now treats agent output as structured Schema.org data and renders supported types directly in the canvas. It also improves the ghost/dry-run workflow by grouping pending approvals into intent groups, letting users select candidate agents, fill one shared disclosure form, and render approved results.

What Changed

• Added a typed renderer for schema:SearchResultsPage and schema:SearchResult.
• Registered the search results renderer in the default block renderer registry.
• Replaced the empty rendered canvas state with the existing intent-browser empty state when there are no blocks.
• Added grouped ghost approvals in the orchestrator/ghost panel.
• Grouped approval blocks by action type and disclosure requirements.
• Added candidate-agent checkboxes inside each approval group.
• Added one shared disclosure form per grouped approval.
• Added Render selected to approve selected agents and flip back to the rendered canvas.
• Added Deny group to reject all approvals in a group.
• Added styling for search result cards, grouped approval cards, agent choices, and disclosure fields.
• Ignored generated Gradle state at bindings/java/.gradle/.

Why

Todd described Papillon as an intent browser:

• users ask for an intent without needing AI,
• Papillon maps that intent to matching agents,
• the user sees a ghost/dry-run canvas before execution,
• agents advertise required disclosures,
• shared disclosure requirements become one approval form,
• approved results render from Schema.org types,
• canvases behave like browser tabs.

This PR starts that flow by making the ghost approval UX and Schema.org rendering concrete.

Testing

Ran:

git diff --check
cargo check --manifest-path apps/papillon/frontend/Cargo.toml
just check-wasm
just run-example pap-search-example

Run browser UI:
env -u NO_COLOR just web

Open:
http://127.0.0.1:1420