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

packages/eval/__tests__/task-loader.test.ts

@@ -0,0 +1,163 @@
+import { describe, expect, test } from "vitest";
+import { parseTaskManifest } from "../src/task/index.js";
+
+const VALID_YAML = `
+name: fix-off-by-one
+description: Fix an off-by-one error in a calculator
+workflow: solve-issue
+prompt: "Fix the bug: add(1,2) returns 4 instead of 3"
+limits:
+  maxSteps: 15
+  timeoutMinutes: 30
+judges:
+  - name: frontmatter-compliance
+    weight: 0.15
+    builtin: true
+  - name: test-pass
+    weight: 0.3
+    entry: dist/judges/test-pass.js
+    schema: schemas/test-pass.json
+`;
+
+describe("parseTaskManifest", () => {
+  test("parses valid task.yaml", () => {
+    const manifest = parseTaskManifest(VALID_YAML);
+    expect(manifest.name).toBe("fix-off-by-one");
+    expect(manifest.description).toBe("Fix an off-by-one error in a calculator");
+    expect(manifest.workflow).toBe("solve-issue");
+    expect(manifest.prompt).toBe("Fix the bug: add(1,2) returns 4 instead of 3");
+    expect(manifest.limits).toEqual({ maxSteps: 15, timeoutMinutes: 30 });
+    expect(manifest.judges).toHaveLength(2);
+  });
+
+  test("parses builtin judge", () => {
+    const manifest = parseTaskManifest(VALID_YAML);
+    const builtin = manifest.judges[0];
+    expect(builtin).toBeDefined();
+    expect(builtin!.name).toBe("frontmatter-compliance");
+    expect(builtin!.weight).toBe(0.15);
+    expect(builtin!.builtin).toBe(true);
+    expect(builtin!.entry).toBeNull();
+  });
+
+  test("parses custom judge with entry + schema", () => {
+    const manifest = parseTaskManifest(VALID_YAML);
+    const custom = manifest.judges[1];
+    expect(custom).toBeDefined();
+    expect(custom!.name).toBe("test-pass");
+    expect(custom!.weight).toBe(0.3);
+    expect(custom!.builtin).toBe(false);
+    expect(custom!.entry).toBe("dist/judges/test-pass.js");
+    expect(custom!.schema).toBe("schemas/test-pass.json");
+  });
+
+  test("defaults limits when omitted", () => {
+    const yaml = `
+name: minimal
+workflow: solve-issue
+prompt: do something
+judges:
+  - name: check
+    builtin: true
+`;
+    const manifest = parseTaskManifest(yaml);
+    expect(manifest.limits).toEqual({ maxSteps: 20, timeoutMinutes: 30 });
+  });
+
+  test("defaults description to empty string", () => {
+    const yaml = `
+name: no-desc
+workflow: solve-issue
+prompt: do something
+judges:
+  - name: check
+    builtin: true
+`;
+    const manifest = parseTaskManifest(yaml);
+    expect(manifest.description).toBe("");
+  });
+
+  test("rejects missing name", () => {
+    const yaml = `
+workflow: solve-issue
+prompt: do something
+judges:
+  - name: check
+    builtin: true
+`;
+    expect(() => parseTaskManifest(yaml)).toThrow("name is required");
+  });
+
+  test("rejects missing workflow", () => {
+    const yaml = `
+name: test
+prompt: do something
+judges:
+  - name: check
+    builtin: true
+`;
+    expect(() => parseTaskManifest(yaml)).toThrow("workflow is required");
+  });
+
+  test("rejects missing prompt", () => {
+    const yaml = `
+name: test
+workflow: solve-issue
+judges:
+  - name: check
+    builtin: true
+`;
+    expect(() => parseTaskManifest(yaml)).toThrow("prompt is required");
+  });
+
+  test("rejects empty judges array", () => {
+    const yaml = `
+name: test
+workflow: solve-issue
+prompt: do something
+judges: []
+`;
+    expect(() => parseTaskManifest(yaml)).toThrow("at least one judge");
+  });
+
+  test("rejects non-builtin judge without entry", () => {
+    const yaml = `
+name: test
+workflow: solve-issue
+prompt: do something
+judges:
+  - name: custom-check
+    weight: 0.5
+`;
+    expect(() => parseTaskManifest(yaml)).toThrow("non-builtin judge must have entry");
+  });
+
+  test("rejects non-object YAML root", () => {
+    expect(() => parseTaskManifest("just a string")).toThrow("must be a YAML mapping");
+  });
+
+  test("rejects judge without name", () => {
+    const yaml = `
+name: test
+workflow: solve-issue
+prompt: do something
+judges:
+  - weight: 0.5
+    builtin: true
+`;
+    expect(() => parseTaskManifest(yaml)).toThrow("name is required");
+  });
+
+  test("defaults weight to 0 when omitted", () => {
+    const yaml = `
+name: test
+workflow: solve-issue
+prompt: do something
+judges:
+  - name: token-stats
+    builtin: true
+`;
+    const manifest = parseTaskManifest(yaml);
+    expect(manifest.judges[0]!.weight).toBe(0);
+  });
+});