feat: eval package scaffold with CLI, schemas, types, task loader

New package @united-workforce/eval (uwf-eval CLI):

- CLI skeleton: run/report/diff/list subcommands (stubs)
- 5 OCAS schemas: eval-run, judge-frontmatter, judge-upstream,
  judge-hallucination, judge-token-stats
- TaskManifest type + parser/validator for task.yaml
- JudgeOutput/JudgeInput types for judge contract
- EvalRunPayload/EvalRunConfig/EvalJudgeRecord storage types
- 19 unit tests: task loader validation + schema definitions

Refs #69

pnpm-lock.yaml

@@ -228,6 +228,31 @@ importers:
         specifier: ^8.0.13
         version: 8.0.16(@types/node@25.9.1)(esbuild@0.27.7)(jiti@2.7.0)(yaml@2.9.0)
 
+  packages/eval:
+    dependencies:
+      '@ocas/core':
+        specifier: ^0.3.0
+        version: 0.3.0
+      '@ocas/fs':
+        specifier: ^0.3.0
+        version: 0.3.0
+      '@united-workforce/protocol':
+        specifier: workspace:^
+        version: link:../protocol
+      '@united-workforce/util':
+        specifier: workspace:^
+        version: link:../util
+      commander:
+        specifier: ^14.0.3
+        version: 14.0.3
+      yaml:
+        specifier: ^2.9.0
+        version: 2.9.0
+    devDependencies:
+      typescript:
+        specifier: ^5.8.3
+        version: 5.9.3
+
   packages/protocol:
     dependencies:
       '@ocas/core':