Test helper: MakeAttempt does not set DifficultyWeight, masking 1.5× Text weighting

[davidortinau]

Background

Surfaced during work on #191 (Wash's vocab-quiz scoring fix, PR #198).

The bug

The test helper MakeAttempt in our vocabulary progress test fixtures (e.g., MasteryAlgorithmIntegrationTests.cs, MultiDayLearningJourneyTests.cs, VocabularyProgressServiceTests.cs) does not set DifficultyWeight on the attempt object. As a result, production defaults the weight to 1.0f for both MC (recognition) and Text (production) attempts.

In production code, MC attempts use weight 1.0f and Text attempts use weight 1.5f (production-recall bonus, lines ~138–144 of VocabularyProgressService.cs).

Why this matters

Tests using MakeAttempt(WasCorrect: true, IsTextEntry: true) do NOT exercise the 1.5× weighting that real Text attempts trigger in production. That means:

• Tests systematically underestimate streak growth from text-entry attempts (1.0× instead of 1.5×).
• During Latter quiz rounds rapidly empty #191's fix, Wash had to pad Tier 1 fixtures from 7 MC + 2 Text to 8 MC + 2 Text because the test was producing mastery = 10/12 = 0.833 instead of the production-equivalent 10.5/12 = 0.875 (just shy of the 0.85 IsKnown floor under divisor 12).

Proposed fix

Either:

1. Make MakeAttempt mirror production's weight defaults: DifficultyWeight = IsTextEntry ? 1.5f : 1.0f.
2. OR pull the weight from the same source-of-truth constant the production code uses (preferred — single source).

Then revert the 7→8 MC padding in #191's fixtures (PR #198) since the original numbers will reflect production weights once the helper is fixed.

Acceptance

• MakeAttempt produces production-equivalent weights.
• All affected test fixtures re-verified with the corrected helper.
• No regressions in PR fix(vocab-quiz): tighten rotation curve for fresh words (#191) #198's now-passing tests.

Cross-references

• Latter quiz rounds rapidly empty #191, PR fix(vocab-quiz): tighten rotation curve for fresh words (#191) #198 — where this was discovered
• tests/SentenceStudio.UnitTests/Integration/MasteryAlgorithmIntegrationTests.cs
• tests/SentenceStudio.UnitTests/Integration/MultiDayLearningJourneyTests.cs
• Wash's history entry (in .squad/agents/wash/history.md) flagging the gotcha