Fold the raycast tool into simulate-mouse-input as a dry-run option #2068

Background

The standalone raycast tool is too small to justify its own tool surface: RaycastTool is a ~110-line wrapper around GameViewRaycastUtility.RaycastFromInputPosition, and its only documented use case is checking what a Game View coordinate would hit before sending a click.

Timing note: raycast was added to main on 2026-07-04 (#1473), after the last released V2 (v2.2.0, 2026-06-26). No release tag contains it, so removing it before v3.0.0 is not a breaking change for anyone — this is the last chance to remove it painlessly.

Proposal

• Add a dry-run style option to simulate-mouse-input (e.g. --dry-run): instead of performing the mouse action, report what the coordinate would hit in 3D physics (hit GameObject name/path, layer, distance, hit point, hit normal, plus CameraName/CameraPath on miss — the current raycast response fields).
• Remove the standalone raycast tool, its skill (uloop-raycast), and its entry in cli/common/tools/default-tools.json (via scripts/sync-tool-docs.sh).
• screenshot --annotate-raycast-grid keeps using the shared GameViewRaycastUtility and is unaffected.

Docs

The Japanese docs (README_ja, whats-new) no longer mention the standalone tool. English docs are synced from Japanese in a later bulk pass.