v0.3.0 — complete the chain: claims and the probe

Completeness: explanations must not omit the connections a learner needs.

• Claims in model.yaml: why, guarantee, mechanism, definition, limit, misconception, each with required fields (a why needs the simplest alternative and its failure; a guarantee needs an example and a counterexample). Renderings mark where they cover each claim (<!-- claim: id -->, data-claim, self.claim()), and explainer check fails on incomplete or uncovered claims.
• Function rule: a function named in model.md (exp, log, sqrt, sigmoid, …) with no why claim fails the check, unless accept_unjustified gives a reason.
• explainer probe: a prompt for a fresh agent that reads only model.md and lists omissions before rendering. On the existing examples it found "why exp" and the Dijkstra negative-edge counterexample.
• Model template: new sections Why this form, Concrete cases, Terms, Scope. Principle 10, "Complete the chain".
• Blind test: claims with ask become quiz questions; the rubric expects their cases.
• Examples: softmax-temperature now explains why exp (with the divide-by-sum and squares counterexamples, live on the page and in the video), why divide by T, shift versus scale, and a worked T = 2 step. dijkstra adds why the smallest estimate, finality with this run's numbers, path reconstruction, and a negative-edge chapter. git-bisect adds the halving trace and a case where bisect names the wrong commit.
• Checks: scientific notation is one number (6.0 × 10⁻⁶); hash fragments like 4e10 stay identifiers; render reports repeated narration lines.
• Docs: authoring guide, model reference, web toolkit reference, docs index, contributing guide.

Full history: CHANGELOG.md