Phase 5: Drift detection & historical reporting dashboard

[ToryMic]

Goal

Turn each SchemaLock JSON report into a historical record so contract drift across deploys/releases is visible, not just pass/fail for a single run.

Scope

• Persist run results (SQLite or flat JSON log) keyed by git commit/tag.
• schemalock diff --from <run> --to <run> — show exactly which endpoints changed contract between two runs.
• Simple static HTML trend dashboard (pass rate over time, per-endpoint flakiness/drift history) generated from stored runs.
• Optional: fail CI specifically on new drift vs. baseline, separate from the existing fixed-contract pass/fail.

Why

Phase 1–4 answer 'does the contract hold right now?' This phase answers 'when did it break, and against what baseline?' — which is what's actually useful once a tool like this is running in CI over months, across many Wave-funded releases.

Acceptance criteria

• Two consecutive runs against different commits produce a diff showing exactly which endpoint/check changed outcome.
• A generated HTML report renders without any server-side component (pure static file).