chore(core): promote alg.rightAnglePath and rightAngle's useModelGeometry to public API

[kumilingus]

Two changesets promoting API introduced (as @internal) by #3457 to the public API in the next minor release:

• alg.rightAnglePath() - the rightAngle router's path-finding algorithm as a public utility
• useModelGeometry option on the rightAngle router

Before merging

• feat(joint-router-avoid): new avoid router package #3457 is merged and released
• Remove the @internal tag (and the "not part of the public API yet" wording) from rightAnglePath/RightAnglePathOptions in packages/joint-core/types/alg.d.ts
• Remove the @internal tag from useModelGeometry in packages/joint-core/types/routers.d.ts
• Resolve the targetInSourceBBox option first - it is flagged in the code as a temporary rightAngle router internal to be removed (deduced inside the algorithm) before the API is frozen

Merge as part of the next minor release train - the changesets bump @joint/core accordingly.

🤖 Generated with Claude Code