Re-add schema changes re: creation and update date

[caufieldjh]

#345 included changes to the schema, UI, and data pages to support sorting by page creation and last-update date.
The latter two sets of changes appear to have persisted - disorder pages include the creation_date and updated_date fields and the disorder browser includes the options to sort by these values (though it does not currently appear to sort anything).

The schema changes got clobbered somewhere along the way (perhaps here: d36bb1a#r177530919). Could be related to Codex working with out-of-synch branches; see #360

This issue is to add the schema changes from #345 back, then check to see if the sorting works as expected.

[github-actions]

Summary

This issue tracks a regression where the LinkML schema changes from PR #345 were lost, even though the UI and data-layer changes from that same PR appear to have survived.

What PR #345 Did (merged 2026-02-16)

PR #345 ("Add sort by creation or updated date") implemented lifecycle metadata for disorder entries:

1. Schema (src/dismech/schema/dismech.yaml) — Added creation_date and updated_date slot definitions with ISO 8601/RFC 3339 pattern validation (^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(?:\.\d+)?(?:Z|[+\-]\d{2}:\d{2})$)
2. Data — All ~100 disorder YAML files and 3 comorbidity files populated with dates derived from Git history via scripts/sync_disorder_git_dates.py
3. UI (app/index.html, app/data.js) — Sort dropdown with 6 options (name/created/updated × asc/desc), date display in disorder cards

Current State

• ✅ Disorder YAML files still have creation_date / updated_date fields
• ✅ The disorder browser UI still has the sort-by-date dropdowns and date display
• ❌ The schema no longer defines creation_date or updated_date slots (confirmed: grep finds no matches in src/dismech/schema/dismech.yaml)
• ❓ Sort functionality reportedly non-functional ("does not currently appear to sort anything")

This means the YAML data files are currently carrying fields that are not validated by the schema — a silent schema/data mismatch.

Root Cause

The schema changes were lost at commit d36bb1a. This is likely related to the parallel-agent branch divergence problem documented in issue #360 — an out-of-sync Codex branch may have overwritten the merged schema changes.

What Needs to Be Done

1. Re-add schema slots for creation_date and updated_date to src/dismech/schema/dismech.yaml under the Disease class, with the ISO 8601 pattern constraint and appropriate descriptions (stable creation_date, update updated_date on content changes)
2. Verify/fix UI sort — the sort-by-date functionality in app/index.html should be tested after schema restoration
3. Run just validate-all to confirm all existing YAML files pass against the restored schema

Related Issues

• Add sort by creation or updated date #345 (closed/merged): Original PR that introduced these changes — can be used as the reference for the exact schema additions needed
• Establish parallel-agent workflow guidelines for shared checkout/branch integration #360 (open): Root cause investigation — parallel agent workflow causing branch-divergence regressions. The schema loss here is a concrete example of the problem that issue proposes to address.