refactor(linkedin-studio): move agent fasit fixtures + tests out of agents/ (v0.5.3)

The 6 long-form-review fasit fixtures (agents/fixtures/*-cases.md) were registered
by Claude Code as junk `fixtures:*` agents because agents/ is scanned recursively.
They are test fixtures, not capabilities. Moved them + their 6 lint tests to
tests/ + tests/fixtures/ and retargeted the 5 agent fasit-refs. Count-neutral
namespace hygiene (ls agents/*.md still 19).

- agents/fixtures/*-cases.md            -> tests/fixtures/        (6)
- agents/__tests__/*-fixture.test.mjs   -> tests/                 (6; ../fixtures -> ./fixtures)
- 5 agent refs ${CLAUDE_PLUGIN_ROOT}/agents/fixtures -> /tests/fixtures
- version-sync 0.5.2 -> 0.5.3 (plugin.json / README badge / CLAUDE.md / CHANGELOG)

Verify: fixture-lint 35/35 at new path; render 20/20, hooks 139/139; test-runner 109/0/0.
Reinstall/reload required for the 6 spurious agents to leave the registry.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CrTb8ktf1XZWEVwgz5MTTo

tests/fact-reviewer-fixture.test.mjs

@@ -0,0 +1,92 @@
+import { describe, test } from 'node:test';
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import { fileURLToPath } from 'node:url';
+
+// Lint-test for the fact-reviewer fasit fixture.
+// Mirrors the structure-only discipline of fact-checker-fixture.test.mjs and
+// editorial-reviewer-fixture.test.mjs: this test asserts the SHAPE of the
+// fixture — the single axis (faktisk-korrekthet), the four checks (F1–F4), the
+// 🔴/🟡/🟢 risk sort, the six Del 4 (Security Champions) cases, the
+// direction-not-copy boundary, and the cold-reader / pivot-risk rationale.
+// Whether the agent's live verdicts actually reproduce the fasit is
+// [GATE]/[OPERATØR], never self-certified here.
+
+const FIXTURE_PATH = fileURLToPath(
+  new URL('./fixtures/fact-reviewer-cases.md', import.meta.url)
+);
+
+const fixture = readFileSync(FIXTURE_PATH, 'utf8');
+
+// The four checks: F1 verifiable claims · F2 quote precision · F3 number
+// attribution · F4 source quality.
+const CHECKS = ['F1', 'F2', 'F3', 'F4'];
+
+// The 🔴/🟡/🟢 risk sort (the emoji are the safest assertion).
+const VERDICTS = ['🔴', '🟡', '🟢'];
+
+describe('fact-reviewer fixture structure', () => {
+  test('names the axis "faktisk-korrekthet"', () => {
+    assert.ok(
+      /faktisk-korrekthet/i.test(fixture),
+      'fixture must name the axis "faktisk-korrekthet"'
+    );
+  });
+
+  test('documents all four checks (F1–F4)', () => {
+    for (const check of CHECKS) {
+      assert.ok(
+        fixture.includes(check),
+        `fixture must reference the check "${check}"`
+      );
+    }
+  });
+
+  test('references the 🔴/🟡/🟢 risk sort', () => {
+    for (const v of VERDICTS) {
+      assert.ok(
+        fixture.includes(v),
+        `fixture must reference the risk verdict "${v}"`
+      );
+    }
+  });
+
+  test('references the PASS/REWORK/BLOCK gate', () => {
+    for (const gate of ['PASS', 'REWORK', 'BLOCK']) {
+      assert.ok(
+        fixture.includes(gate),
+        `fixture must reference the gate decision "${gate}"`
+      );
+    }
+  });
+
+  test('documents exactly 6 Del 4 cases', () => {
+    const cases = fixture.match(/^###\s+Case\s+\d+\b/gim) || [];
+    assert.equal(
+      cases.length,
+      6,
+      `fixture must document exactly 6 Del 4 cases (found ${cases.length})`
+    );
+  });
+
+  test('states the direction-not-copy boundary', () => {
+    assert.ok(
+      /direction, not rewritten copy/i.test(fixture),
+      'fixture must state the direction-not-copy boundary'
+    );
+  });
+
+  test('documents the cold-reader / context-pollution principle', () => {
+    assert.ok(
+      /context pollution/i.test(fixture) && /framing-bias/i.test(fixture),
+      'fixture must document the cold-reader / context-pollution / framing-bias principle'
+    );
+  });
+
+  test('records the pivot-premise-risk rationale', () => {
+    assert.ok(
+      /pivot/i.test(fixture),
+      'fixture must record why the gate exists (pivot premise never met Step 5)'
+    );
+  });
+});