feat: complete the thirteen-stage financial learning path

Server grades levels 7-13 and keeps castle attempt results separate from stored progress.

Co-authored-by: Cursor <cursoragent@cursor.com>

test/integration.test.ts

@@ -428,7 +428,7 @@ async function runTests() {
     assert.equal(levelsMeta.statusCode, 200)
     const levelsBody = parseJson<{ levels: Array<{ id: number; isActive: boolean }> }>(levelsMeta.payload)
     assert.equal(levelsBody.levels.length, GOLD_LAND_LEVELS.length)
-    assert.equal(levelsBody.levels.filter((l) => l.isActive).length, 6)
+    assert.equal(levelsBody.levels.filter((l) => l.isActive).length, 13)
 
     const noAuthProgress = await app.inject({ method: 'GET', url: '/api/gold-land/progress' })
     assert.equal(noAuthProgress.statusCode, 401)