docs: update checkpoints for fixture harness completion

docs/checkpoints.md

@@ -1,6 +1,6 @@
 # Checkpoints
 
-## Checkpoint 0 — Repo skeleton (current)
+## Checkpoint 0 — Repo skeleton (completed)
 
 Delivered:
 - npm workspaces monorepo
@@ -23,6 +23,25 @@ npm run build:types
 
 Gate: do not add runtime or BitVid codecs until fixture corpus exists.
 
+## Checkpoint 1 — BitVid fixture and conformance corpus (current)
+
+Delivered:
+- fixture folders for BitVid cases (admin-state, reports, trusted-mutes, overrides, expectations)
+- import script harness (`scripts/import-bitvid-fixtures.mjs`)
+- characterization cases list (`fixtures/bitvid/characterization-cases.json`)
+- conformance test framework (`tests/conformance/bitvid-fixtures.test.js`)
+- testing utilities (`packages/testing/src/conformance.js`)
+
+Validation:
+```bash
+npm run check:references  # still passes
+npm test                  # now includes conformance tests
+```
+
+Status: Ready for real fixture extraction from BitVid.
+
+Gate: Do not implement evaluator until at least 3 real characterization cases are imported with expectations.
+
 ## Next checkpoint
 
-Checkpoint 1 — BitVid fixture and conformance corpus only.
+Checkpoint 2 — Pure core implementation (target normalization, authority resolution, policy engine)