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/progression.test.ts

@@ -139,7 +139,7 @@ async function runTests() {
     let items = progression.buildLevelItems(TEST_USER)
 
     const playable = getAllPlayableLessons()
-    assert.equal(playable.length, 6)
+    assert.equal(playable.length, 7)
     for (const lesson of playable) {
       assert.equal(countGradableQuestions(lesson), 5, `${lesson.id} should have 5 gradable questions`)
     }