docs: list proposed VC3D tooling PR bundle

[LubuSeb]

Summary

This adds a conservative Community Projects entry for a bundle of open VC3D / Volume Cartographer pull requests currently pending upstream review:

• VC3D: add non-destructive surface view orientation controls #1051: non-destructive active surface-view orientation controls
• VC3D: cast seeding rays on active plane #1053: active-plane point-mode seeding rays
• Make QuadSurface gen safe for parallel rendering #1054: QuadSurface::gen() thread-safety fixes for parallel tile rendering
• vc-render-tifxyz: add opt-in normal direction flip #1055: optional vc_render_tifxyz normal-direction handling

Scope

The entry is framed as proposed work in open PRs, not as merged, awarded, official, or already adopted work.

I placed it near the existing Volume Cartographer entry because all linked changes are focused VC3D / Volume Cartographer usability, correctness, and rendering workflow improvements.

Reproduction / Context

The June 2026 Progress Prize form asks contributors to submit a pull request to scrollprize.org/docs/20_community_projects.md so the community can track public resources and contributions. The open prize page also says progress-prize submissions favor early open-source release, documentation, community-use signals, and VC3D improvements.

This PR is the required community-projects tracking artifact for the linked VC3D PR bundle.

Issue / Artifact Binding

• BountyBar identity: challenge-prize:scrollprize/open-prizes#20260630
• Prize page: https://scrollprize.org/prizes
• Community Projects file: https://github.com/ScrollPrize/villa/blob/main/scrollprize.org/docs/20_community_projects.md
• Linked contribution PRs: VC3D: add non-destructive surface view orientation controls #1051, VC3D: cast seeding rays on active plane #1053, Make QuadSurface gen safe for parallel rendering #1054, vc-render-tifxyz: add opt-in normal direction flip #1055
• Supporting docs PR: docs: refresh active prize count wording #1050
• Artifact: this pull request from LubuSeb:codex/scrollprize-community-vc3d-tooling

Validation

• Validation command: git diff --check
• Result: passed; only the normal Windows checkout LF-to-CRLF warning appeared.
• Manual wording review passed: no claim that the linked PRs are merged, awarded, or used in production.

Known Limits

The linked implementation PRs are still pending upstream review. If maintainers prefer Community Projects to contain only merged or awarded work, this entry can be closed or revised after those PRs are reviewed.

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