fix: make workflow blocker hints actionable

[chtnnh]

Closes #4

What changed

Audits every recovery hint emitted by the pipeline and check path, replacing diagnostic-only or pseudo-shell suggestions with actions that move the workflow forward.

• Changed stale pushed-HEAD recovery from know-code status to know-code taught.
• Added know-code quiz init to create a hash-bound, quota-correct quiz scaffold.
• Added know-code grade propose --write to create a deliberately failing, answer-bound proposal template without forging an approval.
• Replaced broad git add -A guidance with tracked-only git add -u.
• Made the forced-range range begin blocker reachable by removing its contradictory scope condition.
• Replaced remaining changed-hash diagnostic fallbacks with recovery actions.

Verification

• Added end-to-end recovery tests for trailer denial and a pushed HEAD that changed after pass.
• Added a full pipeline recovery-command matrix covering every emitted command: reset, attest-init, range begin, taught, quiz init, ask, proposal writing, grade review, pass, and tracked staging.
• npm run lint
• npm run build
• npm test
• npm run know-code -- check --push

[cursor]

PR Summary

Medium Risk
Touches gate/check recovery paths and writes quiz/grade-proposal files, so wrong hints could send users down the wrong workflow. Scaffolds are failing/placeholder by design, not auto-approvals.

Overview
Pipeline and check denials now point at commands that actually advance the workflow, instead of know-code status or pseudo-shell “write this file” hints.

Adds know-code quiz init (quota-correct quiz scaffold) and know-code grade propose --write (deliberately failing, answer-bound proposal template). Missing-quiz and missing-proposal blockers use those commands. Stale pushed HEAD and changed-hash denials recover via know-code taught or know-code pass. Unstaged tracked edits suggest git add -u rather than git add -A. Range-mode range begin is no longer gated on a contradictory scope check.

Tests cover the full recovery-command matrix plus trailer and post-pass HEAD-change denials.

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[cursor]

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