Import PAP Render with isolated CI

[xtraid]

Summary

• import the PAP Render snapshot pinned at 3eba839fb0bb80a533415eb7c1c793a9edf1a1e1, with MIT license, provenance, update and rollback instructions, and no nested Git repository
• preserve the standalone Python 3.14 project and its 144 collected tests, correcting only the stale README test counts in the upstream snapshot
• run the renderer suite in a separate read-only top-level CI job without adding Pillow or NumPy to the Tiling Foundry root environment

No Wang integration or functional renderer adaptation is included in this PR.

Local verification

• uv run --locked pytest -q under renderer/: 144 passed in two independent runs
• root make check: native suite, 64 Python tests, Pages checks, and benchmark smoke passed
• snapshot inventory and byte-parity checks passed
• workflow syntax/action pinning, diff, secret, artifact, and worktree checks passed