Update add-to-project workflow to add to FOC board

[BigLep]

Done Criteria

Added issues/PRs should add to the FOC board like we do in various FOC repos.
Right now it's added to a FilBeam board which can be deleted.

Why Important

Visibility of issues/PRs
Get rid of noise like https://github.com/filbeam/worker/actions/runs/28537456604

Notes

[BigLep]

Opened PRs to move the add-to-project automation from the FilBeam board to the FOC board (FilOzone project #14) across the three repos:

• ci: add issues and PRs to the FOC board instead of the FilBeam board #697 — replaces the old add-to-project.yml (FilBeam board Purchase FilCDN domain #4) with the canonical FOC workflow. Closes this issue on merge.
• ci: add issues and PRs to the FOC project board contracts#18 — adds the FOC workflow (repo had none).
• ci: add issues and PRs to the FOC project board docs#9 — adds the FOC workflow (repo had no workflows).

All three target the FOC board and use the improved canonical workflow (v2.0.0 pinned, pull_request_target for fork/dependabot PRs, continue-on-error, permissions: {}). rjan90 is requested as reviewer on each.

⚠️ One prerequisite: the ADD_TO_PROJECT_PAT secret needs access to the FilOzone FOC project (#14); it previously only needed the FilBeam org project (#4). If the PAT isn't scoped to the FilOzone project, the add step will fail (silently, due to continue-on-error). Worth confirming/updating the PAT before relying on this.

[BigLep]

Updated all three PRs to use the FILOZZY_CI_ADD_TO_PROJECT org secret (now created in the filbeam org), matching the FOC repos — the workflow files are now byte-identical to the FOC canonical template. The earlier ADD_TO_PROJECT_PAT prerequisite no longer applies.