Validate MMED schedule data via the shared pre-commit hook (#54)

[WestonVoglesonger]

Makes MMED pull the shared schedule validator in as a pinned pre-commit hook, rather than vendoring its own copy. Reshaped to the Path A model: the validator, JSON Schema, and role vocabulary live once in ICI3D.github.io (now packaged and exposed as a pre-commit hook), and MMED consumes them with no duplication and no per-clinic maintenance.

What's here

• _data/schedule/mmed/2025.yml — MMED's own schedule data (extracted from the live wall). MMED owns its data; it lives here, not in the shared theme.
• .pre-commit-config.yaml — pins the shared validate-schedule hook. Contributors get the same check locally on every commit (pip install pre-commit && pre-commit install), and it runs in CI via pre-commit/action, so local and CI validation are one source of truth.
• .github/workflows/schedule-validate.yml — runs that same hook on push/PR. Checks out the ICI3D.github.io submodule only for its shared people records (the hook's --people-dir), which is how instructor keys resolve today, the same records the Jekyll build reads.

Why this shape (vs. the earlier composite-action version)

The schema and validator are pulled in by pre-commit, not by a submodule path, so contributors run the identical check locally before pushing (the original ask in #54), not only in CI. Nothing clinic-specific is maintained here beyond the data file and a few lines of config. A new clinic drops in the same .pre-commit-config.yaml + its own data.

Verified locally

The shared validator reports 0 errors / 0 warnings on this data, resolving MMED's instructor keys against the 69 shared people records in the ICI3D.github.io submodule. This is the exact path the hook runs.

Draft — depends on the theme PR

The hook currently points at the fork branch carrying the packaged validator (WestonVoglesonger/ICI3D.github.io, pinned by sha), because ICI3D/ICI3D.github.io#59 is not merged yet. Once #59 merges, flip the hook's repo: to ICI3D/ICI3D.github.io and rev: to the merge sha/tag. Until then this is a working preview against the fork.

Follow-up (not in this PR)

Rendering still comes through the submodule. Moving MMED's rendering to remote_theme: ICI3D/ICI3D.github.io (dropping the submodule, and having MMED own its _data/team) is a separate, site-build-affecting change and the #56 topology call. This PR deliberately touches only the validation channel, which is safe and independent.

Supersedes #25

Closes out the earlier spike (#25), which put the tools/schema/renderer in MMED instead of pulling them from the theme.

Part of #54 / epic #58.

[WestonVoglesonger]

@pearsonca reshaped this to consume the shared validator as a pinned pre-commit hook instead of a composite action through the submodule, so contributors run the same check locally, not just in CI.

• .pre-commit-config.yaml pins the validate-schedule hook; the workflow runs it via pre-commit/action; _data/schedule/mmed/2025.yml is MMED's own data.
• Validation channel only. Rendering still comes via the submodule; the remote_theme swap is the separate #56 call and is not here.

Verified: 0 errors / 0 warnings on MMED's 2025 data against the 69 shared people records. Draft pending #59; the hook points at the fork branch for now and flips to upstream at the merge sha once #59 lands.