fix(packaging): include beta 11 schemas in sdists

[bokelley]

Summary

• update the tracked sdist schema-cache include from AdCP beta.10 to beta.11
• extend the existing distribution-manifest pin test to cover the source cache consumed by sdist-to-wheel builds

Root cause

#1114 updated the wheel package-data pin, but #1118 had concurrently introduced a second MANIFEST.in pin for source distributions. That source pin remained on beta.10, so the regenerated beta.12 release PR could build an sdist but failed when building its wheel because schemas/cache/3.2.0-beta.11 was absent.

Verification

• pytest tests/test_schemas_version_pin.py -q (8 passed)
• clean Git archive, Python 3.11 python -m build
• verified the resulting wheel contains adcp/_schemas/3.2.0-beta.11/index.json

Blocks the finalization of generated release PR #1119.

[aao-secretariat]

Ladon verdict: Approve

Approve.

Corrects the sdist source-cache MANIFEST.in pin from 3.2.0-beta.10 to 3.2.0-beta.11, aligning it with ADCP_VERSION and the wheel _schemas pin, and adds a version-pin test assertion guarding the previously-drifting second manifest include. Verified: beta.11 cache subtree exists with real JSON, fix(packaging): prefix carries the correct non-breaking semver signal, and no public surface or wire shape changed.

No blocking or medium findings. gated_paths is false, high_risk is false, no author-team gate, and no critical/high findings — falls through to row 9.

[bokelley]

All 26 checks are now green, including the clean sdist-to-wheel downstream import smoke that reproduced the release failure. Auto-merge is armed. @andybevan-scope3 @BaiyuScope3 @KonstantinMirin @rachitm022 — an independent approval on this final head will unblock regeneration and publication of Python beta.12, then protocol RC.0.