fix(tutor-quality): check every Topic an Example activates for a masterable LEARN path

[ttbombadil]

Purpose

The authoring gate missed the most severe deterministic Tutor defect in the production catalog. This PR extends it with a generic invariant, so that the anchor corpus and the real Course Content cannot drift apart unnoticed again.

Finding

tutor-quality-validator checked prerequisites, mastery capacity and the executable LEARN path only for Topics that a quality case expects. A Topic that a real Example merely activates was never checked.

In ttbombadil/unosim-examples (2ac716f, the default Course Content source in server/config.ts), variables-and-serial is activated on 16 of 35 Examples and unresolved from the first turn: its Concept serial-output required an int-only prerequisite. On those Examples the Topic-driven Tutor never serves a planned question and stays content-exhausted for the whole session. The content fix is in ttbombadil/UnoSim-Examples#4.

Invariant

For every Example in the manifest and every Topic the production matcher activates on its main sketch, a learner who answers every planned question successfully must reach Topic mastery. The path uses the production planner, Topic classification and the Example's effective LEARN strategy.

• It needs no quality case, no list of known Examples or Topics, and no provider.
• It finds Topics that are unresolved from the first turn: unprobeable prerequisites, missing applicable questions, insufficient mastery capacity.
• Legitimate later exhaustion is not forbidden: neither exhaustion after weak answers (the strong path is the best case) nor post-mastery (DEEPEN) capacity is checked here. DEEPEN capacity stays checked for expected Topics only, as before.
• New issue code unmasterable-example-activation carries exampleId (also printed by the CLI).
• The strict LEARN loop is extracted into strictLearnPath and shared with the existing per-case check; that check's behavior is unchanged.
• TutorQuality SSOT §4 documents the invariant.

RED / GREEN

	result
6 new validator tests (unprobeable prerequisite; same Topic without it; probeable prerequisite; Topic not activated; later exhaustion allowed; Example strategy used)	RED (function missing) → GREEN
directory test: Example without quality case activates an unmasterable Topic	RED with the old directory validator → GREEN
validate:tutor-course-content on real content 2ac716f	exit 1, 16 × unmasterable-example-activation (exactly the 16 known Examples, nothing else)
same on the content fix (UnoSim-Examples#4)	exit 0

Rollout order

1. Merge UnoSim-Examples#4 first. Its CI still uses the validator pinned at aaa52fad and passes.
2. Merge this PR.
3. Then bump .unosim-compatible-commit in UnoSim-Examples so that its CI enforces the invariant.

Merging this PR before #4 makes the local validate:tutor-course-content against the current content red. UnoSim's own CI is unaffected, because it uses synthetic fixtures.

Gates

Gate	main (db272a84)	this PR
npm run check	0 errors	0 errors
npm run test:tutor-quality	380	387 (1.7 s / 15 s)
npm run test:unit	2642 + 1 skipped	2649 + 1 skipped
npx eslint . --ext .ts,.tsx	0 errors / 10 warnings in tracked files	identical
npm run check:docs, git diff --check	pass	pass
pre-push (unit + Sonar)	–	pass, quality gate PASSED

No provider calls; no prompt, Judge, criteria or verdict change.

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